RevoMini Serial2

I have tried to compile my own firmware, but I do not seem to be able to get it working.
I want to get a third Serial on the RevoMini by sacrificing two PWM outputs (PA0 and PA1).
I tried to modify the hwdef and compiling works, but I do not seem to able to get it working (a connected GPS does not get recognised).

I have attached the original and modified hwdef files. Anyone can help?

hwdef.dat.txt (2.7 KB) orig_hwdef.dat.txt (2.9 KB)

Found a working solution: in Serail-order Serial 2 has to remain “EMPTY”, Serial 4 gets set as UART4 and it suddenly worked.