My black screen of death experience

[Amamba]

Don't know if anybody else had this issue. My 4 months old unrooted all stock phone wouldn't wake up. I could reboot it and use it normally but once the screen went black that was it. I disabled fastboot, pulled SD, did a factory reset but none of it helped. Setting it to never go to sleep didn't help either. Took it to sprint store where they tried to reset the battery connector but that didn't do anything either. I finally gave in and paid $35 to have the phone swapped rather than having to wait 2 weeks for HTC to fix it under warranty.

I suspect that the latest system update may have had something to do with this. I am hesitant to update the replacement phone now. Just wondering if anyone else has had a similar experience and if there is a known cause.