Rooted TF300T is continually rebooting into TWRP...

[droidbound]

Your first mistake probably was that you did not format /data coming from Crombi. You just wiped it and that is not enough if you switch Android versions.
And then you made the cardinal mistake of using Wipe Data from the bootloader with a custom recovery installed. Don't beat yourself up too much though, you really could not know that unless you spent countless hours in these forums like I do.
But YOU probably have a life, so... it's fine, never mind

My pet theory is that you have the Wipe Data command stuck on the misc partition. Each time you boot, the bootloader finds that command and calls the stock recovery to perform a wipe. Unfortunately nobody is home since you replaced it with TWRP, which makes a valiant attempt to comply and .... fails. Since the wipe does not happen, the command does not get erased and there you are in a nice little catch22.

There are two ways to go about this and we start with the easy one. We will overwrite the misc partition in adb shell, erasing the command, and next time you boot you should be able to boot to the bootloader and hopefully even into recovery. Don't even try to boot the rom at this point, that's a different problem.
If I am correct - it does happen once in a while - you would enter TWRP, properly format /data and then reflash the rom.
The end

Oh yeah, right! You need a couple of commands to get there!
The following will only work if you have a minute or two before TWRP reboots, if you do not have that much time we probably have to go another route, but for several reasons I want to try this first.
So test out at what point you have an adb connection. When you do, run these commands, hit enter at the end of each line (make sure you're running Windows as administrator!):

adb shell
killall -19 recovery
dd if=/dev/zero of=/dev/block/mmcblk0p3 bs=64 count=1
reboot

Have the dd command ready copied on your clipboard so that you can paste it. You do not want to rush typing dd commands!!! A tiny mistake can ruin what you left intact so far
Be careful!
When the tablet reboots just hold the Vol Down button until you get to the bootloader. Enter recovery through RCK, then go to Wipe > Advanced > Format data > type "yes" and go have coffee. The formatting can take up to an hour. DO NOT RUN OUT OF JUICE.
Ok, try that and report back

[emailcraigs]

Well, I tried this when it was stuck on the teamwin splash screen. At this point it responds to the adb devices command showing 015d2d42454c2413 and recovery. When I put in the commands it echoed them back to me each time but no reboot.

I finally held the power button and vol- and it started rebooting continuously again. When its doing this I cant get it to show anything for adb devices even though I hear the usb initialize. It shows the ASUS name, then it shows the 4 penguins in the top left, and then it goes to the teamwin splash screen. It only stays on this splash screen for 29 seconds and I never see a reply to the adb devices command.

I only seem to see the responses when it gets stuck on the splash screen. This happens when I leave it alone for awhile charging. At the moment I'm waiting to see if it will go back to being stuck on the splash screen so I can try again, but it doesn't seem like its taking the commands?

[droidbound]

If you don't get a return for 'adb devices' you don't have an adb connection. That is crucial. Without it the tablet is dead, so find out how and at what point and for how long you do have an adb connection.
No use putting in the commands without a positive return.

Edit: Ok, re-reading your post, you did try it when you got the serial # in recovery back, right? And you ran Windows as admin?
If all of the above is true, this is a dead end and we have to go to plan B. Let me know

[droidbound]

Ok, don;t know what time zone you are in, but I'm going to bed real soon, so here is Plan B:

[GUIDE] Help! My Transformer TF700 boots only to recovery!!!!

You may need a few tries to push bootit.ko to your tablet's internal storage and we may have to test if the file gets pushed ok if you do not get a positive result right away, but for now just follow that guide and report back.
Yes, the guide was written for a TF700 but it works just the same on the TF300. That's tried and proven...
DB out for the day..

Edit: Oh! And never underestimate switching or changing USB ports in Windows (with or without a reboot). what does not work on one may work on the other or on the same port after a reboot.... There's no rhyme or reason to this, just black-box-monkey-see-monkey-do try whatever....

[emailcraigs]

yes, when it gets stuck on the teamwin splash screen I get a reply back for adb devices showing:

015d2d42454c2413 recovery

That is when I submitted the commands. I ran the command window as admin when I tried the commands from the adb folder. I'm pretty sure it was connected because I got into the adb shell, right? Otherwise it says error: device not found.

[emailcraigs]

Cool, as soon as I can get this thing to hang on the teamwin splash screen I'm going to follow those directions. I'm not sure what makes it hang on that screen occasionally but its the only time I get a positive reply back from adb devices and can get into adb shell.

[emailcraigs]

Ok, don;t know what time zone you are in, but I'm going to bed real soon, so here is Plan B:

[GUIDE] Help! My Transformer TF700 boots only to recovery!!!!

You may need a few tries to push bootit.ko to your tablet's internal storage and we may have to test if the file gets pushed ok if you do not get a positive result right away, but for now just follow that guide and report back.
Yes, the guide was written for a TF700 but it works just the same on the TF300. That's tried and proven...
DB out for the day..

Edit: Oh! And never underestimate switching or changing USB ports in Windows (with or without a reboot). what does not work on one may work on the other or on the same port after a reboot.... There's no rhyme or reason to this, just black-box-monkey-see-monkey-do try whatever....

I'm still trying to get back to that mystical stuck teamwin splash screen. I'm not sure what makes it do that but its the point where I get connected. I was wondering if its when I let it drain the battery down to a turn off point. I'm also trying that along with usb port changes and reboot combos. Sooner or later its got to do it again.....

[emailcraigs]

Ok, don;t know what time zone you are in, but I'm going to bed real soon, so here is Plan B:

[GUIDE] Help! My Transformer TF700 boots only to recovery!!!!

You may need a few tries to push bootit.ko to your tablet's internal storage and we may have to test if the file gets pushed ok if you do not get a positive result right away, but for now just follow that guide and report back.
Yes, the guide was written for a TF700 but it works just the same on the TF300. That's tried and proven...
DB out for the day..

Edit: Oh! And never underestimate switching or changing USB ports in Windows (with or without a reboot). what does not work on one may work on the other or on the same port after a reboot.... There's no rhyme or reason to this, just black-box-monkey-see-monkey-do try whatever....

OK, it took a bit of maneuvering but I am now back into recovery and have fastboot access. I got the screen to hang, the file transferred fine the first try, but then it took some persistence to get the insmod command to run, but it did eventually. From there it was pretty smooth sailing. My custom recovery was not working so I flashed it again from fastboot and now have full TWRP recovery access. Much appreciation for your time!! I will never make the mistake of using wipe data from the RCK screen again!! I can tell you that.

I've read quite a few posts where you have helped out poor souls like me. Your sacrifice of your time is admirable. Thanks again!!

[droidbound]

Glad you got it back! Good job!

[emailcraigs]

OK, it took a bit of maneuvering but I am now back into recovery and have fastboot access. I got the screen to hang, the file transferred fine the first try, but then it took some persistence to get the insmod command to run, but it did eventually. From there it was pretty smooth sailing. My custom recovery was not working so I flashed it again from fastboot and now have full TWRP recovery access. Much appreciation for your time!! I will never make the mistake of using wipe data from the RCK screen again!! I can tell you that.

I've read quite a few posts where you have helped out poor souls like me. Your sacrifice of your time is admirable. Thanks again!!

I did get it back, but ended up with some partition problems with TWRP not being able to mount any partitions. I'm working through that now using some more of YOUR good advice on other threads. I wanted your opinion on something though....is KANG TWRP 2.8.7.2 a recovery that I should be using to go with KatKiss 7.1 023 on the TF300T? Its recommended but then I have read that some think 2.8 has bugs and went back to 2.6. I guess the latest TWRP isn't recommended for the katkiss ROM.