This can happen without Jailbreak/deliberate clock adjustment.
I have had this happen to an iPod 1 (so IOS 5 or 6) device where my son tried the PIN sufficient times to lock it out and say try again in (approx.) 46 years.
The iPod is not jailbroken and I know for sure that the clock was not adjusted manually. The only other explanation could be that (since the battery is knackered) it is something to do with it re-synching its time when it is connected to power and hence WiFi.
The fix is to reconnect it to iTunes and do the DFU (can't do this as there are no more firmware updates for a device this old!) or restore process via a PC/Mac with iTunes.
The restore will of course only take you back to the last backup for the device (in this case on iTunes)….