I'm guessing it's cheaper to buy a new phone than to repair it, but hard to say.
And you should see that red text saying blk0 or whatever if it's hardware failure. Otherwise it could just be ROM issue.
You could try flashing this:
BASE - [ODIN] DarkyROM 10.2 Resurrection GT-I9000 | DarkyROM although I don't see why my "Phase R: Flash UGKG3" wouldn't have worked.