We should try two more things.
Can you do a loopback test of your serial port?
If you have a jumper wire, connect TX and RX together. Then start minicom.
minicom -b 9600 -o -D /dev/serial0
+Do you see extra characters in minicom?
+When you type within minicom, do you see the characters you type?
finally, can you upload a close up photo here of the header and gps part of the BerryGPS-IMU.
Mark --OzzMaker.com --