Everything is powered from the craft,
So if craft loses power, so does camera, and wifi! Wifi has nothing to do with controlling the craft, only links your camera to your smart device!
In other words if wifi was to go out completely, your craft will still fly, same as if you removed the camera completely, you can still fly! So this tells me you have a bigger problem!
I had a battery that went bad, not fully bad, but at 100% charge I'd lift off, within 30 seconds or so, the craft would go all red flashing, warning buzzer going off, and craft would land, I had little control during the event! But yours sounds like it's coming down hard and fast, mine had a decent descent, kinda quick, but not crazy? If all else fails, try reinstalling your firmware, on Tx, and bird, also make sure you have fresh batteries in your Tx, after update, calibrate Tx through RC ASSISTANT, then hook bird to PC ASSISTANT, calibrate Tx there as well, do an ADVANCED IMU CALIBRATION ( make sure bird is STABLE and LEVEL during this part, then go out do a fresh compass calibration! Something might be out of whack?
( also have you crashed? )
You might want to check your GPS unit, to see if the CERAMIC antenna is cracked, this can cause loss of GPS signal, causing craft to go stupid! I would just scrutinize EVERYTHING!
Keep us posted!
Jerry
J Dot
Take Care, Fly Safe!