Old battery draining too fast,
Literally 12 hours before my repair was going to start my phone died a gruesome death. Once I buy more replacement parts I look forward to using the kit I bought to fix it.
When you spend all day working on a phone, take a break. The effects of fatigue will inevitably lead to a mistake that could be critical. Off all my electronics mods over the years fatigue has claimed 2 expensive machines.