Dump the battery and run with charger, set a fan up to cool your phones, dump 20-30 of them in an mineral oil tank to cool them, take the plastic shell off to help with cooling etc etc. Like I said "if you know what you're doing".
That is no longer mobile nor a phone.
The only time I'd consider mining with a phone is if I was stranded in a broken down car in a blizzard
and it was my only source of heat.