I had the same problem w/ my Titan! Did the same exact thing before and after it happened! Used 3.16 but unsuccessful and went back to the original ROM release. Next, thing u know, black screen of death! Looks like it goes to sleep and stays stuck in the sleep mode or reverts back to sleep mode after pushing the button. Definetly a firmware issue.
Well, luckily for me...I have insurance!
I took it to the shop told them I flashed the ROM to 2.17 and it never worked the same. True story. Within minutes,the tech said we're just gonna get ya a new one instead of spending the time to figure it out. I asked him when will the replacement arrive? He said in 2 business days. I said SWEEET! Got me a brand new Titan that I really really like and for no money outta my pocket! No deposit, no nothing! My old one had alot dings and dents so that's another plus.
I would try and flash the ROM to the original release and see if that works and if that doesn't work...get insurance and use the same line I did. After all, you did techically upgrade the firmware.
Good Luck!