i resurrected my boss' 7105t last week, after his suffered the same fate. even though i got it up and running again, the error did recur (i have no idea what he did!), so you may still want to replace the hardware. by using the following, you too can have your very own FrankenBerry!
go to this thread
and read through the first post. the JLAWD
is your friend.
after you've downloaded, installed and ran as jjoyner (rockstar!) instructs, you'll have a clean 'berry with nothing on it.
(some users may have need/want to delete the infamous vendor.xml file from its resting place, although oven temps may vary.)
start BB Desktop Manager, and then plug in the juiced 'berry. it should be (un)recognized as new hardware, and then using AppLoader, you'll be able to install your choice of available handheld OS software.
once the basic OS is installed, you'll have enough to execute a restore using a previous backup.
everything listed here to fix your 'berry is described in detail elsewhere in the forum. this fix uses a simple combination of otherwise easy tasks. the only real catch is that since the handheld simply won't boot, you need to totally kill it before you can heal it.
as always - if you are unsure, or have questions, ask away!