The Remote firmware has the Raspberry Pi locked out from using the serial connection, but with I2C1 it can be enabled. One of the status bits is for host lockout. I2C command 7 is used to set that status bit.
python3 import smbus bus = smbus.SMBus(1) #write_i2c_block_data(I2C_ADDR, I2C_COMMAND, DATA) bus.write_i2c_block_data(42, 7, ) #read_i2c_block_data(I2C_ADDR, OFFSET, NUM_OF_BYTES) #OFFSET is not implemented print(bus.read_i2c_block_data(42,0, 2)) [7, 0] exit() picocom -b 38400 /dev/ttyAMA0 ... Terminal ready /1/id? # C-a, C-x.