My first FP2 was a disaster. The proximity sensor did not work, the screen stopped responding occasionally, the phone restarted frequently and I also had problems with the GPS. Also the bottom module broke (I could not charge the phone) and finally the core module just died.
The replacement was a refurbished FP2, and I was happy with it until now. But now the bottom module broke again. I still can charge the phone but the caller cannot hear me unless I switch to the speaker mode (which apparently uses a second micro.)
Maybe I am breaking these bottom modules by using a battery pack while riding my bike but the phone is mounted so there should not be much strain on the USB plug. But what do I know, maybe the phone is just not built for me.