So apparently, the guys at QJ say the Downgrader is fake. BUT! they have Dark_Alex behind them. I'm not positive that this will brick your PSP, but it could mess it up, if it is fake.

Here's D_A's reasons:
# Some games will lock up in 2.71 SE-C.
# On 1.50, trying to change settings menu gives a Blue Screen of Death. You won't be able to change your Video Options, System Settings, etc.
# On a brighter note, the BSoD could theoretically be fixed, using an app like X-Flash to flash a new system reg from a 1.50 user! Or, while making the dump, switch the 2.50 reg with the 1.50 reg. This is risky however.
# The TA-082 Boards can also be downgraded to 2.71 SE-C! The BSoD will be gone. The catch again, you may not be able to return (to 1.50). If you can, it will most likely use the same update made to downgrade from 2.50. That still has not been tested.
# Using this to downgrade to either 1.50 or SE-C leaves you with that particular state. Attempting to upgrade, according to 0okm, will most likely brick your PSP so you probably shouldn't try it.

[Source]

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