Rpi wont boot anymore - overvoltage?

[Pitter]

Hi,
since yesterday my rpi wont boot anymore. Its a Model B. What happend?

-Power over GPIO-Pins
-used a ubec
-the ubec obviously changed the voltage from 5 to 5,3 (measured afterwards)

Dont know if the last point is the reason why it doesnt boot anymore. Right now it behaves as follows

-5V from stable source via Micro-USB
-red light comes on
-TP1 => TP2 4,3 Voltage BUT dropping if i connecting 5 V longer (30 sec), dropping to 1,2 V finally
-F3 seems to be free ! (multimeter)
-but: F3 gets hot !


My questions: is the rpi permanently damaged? How to analyse that? Can still the fuse be the problem? Why does the voltage drop constantly?

Most important: how can i power a Model B without micro-USB BUT STILL BE PROTECTED by the fuse? On my B+ i found information about that (P2 und P3....) but for B i dont find anything.

Thank you all.

[RaTTuS]

5.3V over GPIO is not good
power via micro usb will be fuse protected
5V +/- 5% == 4.75V-5.25V nice range 5.3V is just outside that
if the SOC get hot then it is dead
F3 you may be OK

[Pitter]

Additional question:

at the time it happend a Wifi-stick was connected. This stick was modified, at the contacts of the stick (+, -, data+, data-) i did soldering. Maybe there was a short between + and data+. Could this have been the problem?

[davidcoton]

Additional question: Could this have been the problem?

Yes. Such modifications are always a risk.

Leave your Pi unpowered for one or two days and try again -- if its a polyfuse problem, it will probably self-heal.

Always power through the micro USB if possible, to preserve the protection provided on the board. If you must power through the GPIO connector, provide your own protection. And if you applied 5V to the wrong pin, it's time to buy a new Pi.