Ok so I'm trying to boot up my Toshiba Satelitte c655 and it freezes to a black screen w/ a still ( _ ) in the upper left hand side. My hard drive is removed due to it not working and I was booting Linux Mint 12 via thumb drive. I cant even get into my (h2o insyde) BOIS due to password lock and tried removing the battery under keyboard and also shorting out the B500 solder pionts. Any suggestions??
I would recommend resetting the CMOS battery, your system may have a button to do this or you might have to do it manually. This will reset your BIOS password and it means that you will be able to go onto that, its a good start.
Probably not it, but I recently was changing S-ATA HDDs and a few times on boot-up the caret was flashing in the same place as you mentioned, with only the caret on-screen; I realised it was the boot order in the BIOS (since changing HDDs over to different S-ATA ports messed the settings) and it was quickly remedied. I hope the fix is as simple for you as it was for me.