Chosen Solution
Just replaced the motherboard in my 16gb 4s with a 64gb motherboard. Works great but crashes at least once an hour. Both are a1387 iPhone 4s. No other obvious symptoms. Any ideas?
Are you using the same battery from the other phone? And what do you mean by crashing? Is it like Apple logo when it soft reboots by itself? Or shut off and turns itself on again. You will notice a different between a reboot and a soft crash. One will take longer and the other shorter. Could be a bad logic board especially with power management chip or gas gauge chip for reading the battery.
