12-13-2021, 04:38 AM
Those are test pads. The two on the very right can be shorted to enter the modem's EDL mode (instructions). They are listed as T1500 and T1501 in the schematics. I don't know about the other ones, but they might be T500-503 (T503 would be for FEL mode which would make sense to be accessible, hence my guess).