How to: Downgrade/Debrick PlayBook from Beta OS 188.8.131.520
Update: While I have not personally tested it, I've heard that the small update to 2.1 which was pushed out on Sept 24th allows you to downgrade using DM. If it does, awesome. If not, the below method should still work (until RIM blacklists 2.0.1 entirely).
It seems like a lot of people have been posting because they've been having problems with the latest PlayBook Beta OS, 184.108.40.2060. Normally this wouldn't be an issue, because up until now you could always downgrade your PlayBook from a beta by debricking it. This is not the case with 220.127.116.110.
When RIM released PlayBook OS 18.104.22.1688, they intended that to be the only official OS which people would be able to run; as a result, in 22.214.171.1240, they blacklisted 126.96.36.1998. When 188.8.131.528 was pulled (whether due to issues upgrading from version 1.0 OSes or issues with the battery levels being improperly detected), there was no official means to downgrade from 184.108.40.2060.
There is, however, an unofficial way to downgrade. I've set it up here in a way that it requires very little computer savvy-ness. Keep in mind that this method is UNOFFICIAL, and will VOID your warranty. It is also NOT GUARANTEED to work, and it is NOT my fault if any damage occurs to your PlayBook, your sanity, or your consortium.
This method required using CFP, which is a PROPRIETARY internal piece of RIM software that is not intended to be given to the general public.
ALWAYS BACK UP YOUR PLAYBOOK BEFORE YOU DO ANY OS CHANGES ON IT!
With all that out of the way, lets begin.
Step 0: Connect your PlayBook to a working PC (sorry mac users, I refuse to support your lifestyle choices ;)) with an internet connection, and have a substantive understanding of the English language.
Step 1: Create a new folder on your desktop. You can name it whatever you want, but make sure you remember the name and do not put anything in it except what you download to follow these instructions.
Step 2: Download a PlayBook OS you want to downgrade to and save it to a folder OTHER THAN the one you created in step 1. Your downgrade choices here are very limited. It is confirmed that downgrading to 220.127.116.118 will work, and you can download 18.104.22.1688 directly from RIM.
I suspect that 22.214.171.1240 will also work, but I have not tested that.
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Step 3: If you downloaded the .bar for 126.96.36.1998, rename it to .zip (or just open it as an archive) and extract the .signed file (just the .signed file, none of the other files/folders) to the folder you created in Step 1. If you downloaded the .zip I provided for 188.8.131.520, extract the .signed file to the folder your created in Step 1.
Step 4: Download cfp to the folder you created in step 1.
I do not know where you will be able to find cfp, it is proprietary RIM software. However, I suggest you check This Link created by Lyricidal.
Step 5: (Optional): This step is for people who do not wish to use the command line.
If you are using 184.108.40.2068, download this file into the folder you created in step 1: loadOS220.127.116.118.bat
If you are using 18.104.22.1680, download this file into the folder you created in step 1: loadOS22.214.171.1240.bat
Step 6: If you did step 5, just click the .bat.
If you didn't, just run cfp load osname.signed from the cmd window.
Do not disconnect your PlayBook until the downgrade is complete.
That's it. Your PlayBook should load the OS, and everything should be good to go. After the OS finishes installing and your PlayBook boots up, I recommend you delete any files you downloaded in the course of the downgrade.