I would be checking voltage on each network A and B if I remember check on the unused network first ….should be around 13.8 dc think you have 4 to check
Pyronix 76 ….wifi xa card …..cheapest option but app on subscription after 1st year
Premier 24 plastic , keypad , smartcom ….app free ( no guarantees it may go to subscription)
You don’t have much choice anymore ….texecom Veritas , the full size is better than the compact version as you can fit a larger battery , have you checked the internal speaker ? If it’s blown then you won’t get any bleeps from the keypad
11 volts ? That’s too low …I would wire the keypad direct onto the panel network with nothing else on the network to see if it works it could be one of the data lines down to the keypad …