If the M1 is starting with a transformer connected when you turn on the power switch, it is looking more like the power supply on the M1. If the transformer was not working, the M1 will not start with a battery connected until the startup pads are shorted on the PCB. A working transformer will start the M1 when the power switched is turned on.
An item to check is the voltage on the transformer. If it is low voltage on its output, the battery could not be charging properly.
The transformer has an auto reset fuse built-in rated at 4 amps. The M1 also has auto reset fuses.
If the transformer is extremely hot, the auto reset fuse could have shut down the transformer. Unplug the transformer and let it cool down if it is hot. This could reset the fuse in this case. There could be enough leakage current on the auto reset fuse to start the M1.