Factory reset seems to have killed it

[androidmog]

Just been given my brother's old Note 4 as a backup. Charged it up and it worked fine. On 02 Network in UK but no SIM in the phone. It still had all his accounts on it so I decided to do a factory reset. As soon as I hit the reset button the screen went off and the phone appears to be totally dead, not even responding to the battery charger. Any ideas about how to resurrect it?

 

[ocnbrze]

can you boot up into recovery mode? if so you can try a hard reset.

 

[today]

Could be battery problems. Too much work for a bad battery. I've got a HTC that won't do anything without being plugged in and if I ask too much while plugged in like a game it can and has shut down and reset.

 

[androidmog]

I realised that it didn't have a sim card in it. Put one from another phone in and it came back to life when I did a hard reset (vol +- power button). Had a "Downloading do not turn off target" message on the display, but it does again a while later. The phone is probably locked to the 02 network and the SIM was a different network, so that may have something to do with it.

 

[Hadron]

I suspect that putting the SIM in was pure coincidence - there's really no reason a phone won't boot without a SIM, even less reason it wouldn't even start to turn on. Perhaps leaving it on charge for a bit is what did the trick: when a battery is really flat it may only trickle charge for a bit until it gets into its normal operating range (i.e. the level at which it is safe to charge normally), and it may well not respond to the power button if it's in that state.