Max! eq3 cube issues

Hi
I own a max! eq3 cube with wall and radiator thermostats. Since I had issues with the cube reseting every now and then, I flashed it with the CUL/CUN firmware and it worked well for several months.
However I now have some issues : it seems the communication b/w the wall thermostat and/or the cube is failing and the thermostats have consumed a whole set of batteries in 1 month where the previous ones lasted almost 1 year, and nothing have changed (position or composition)
I would bet that it is the communication between devices and the cube that fails since even valves not linked to a wall thermostat seem to drain the batteries.
Any idea how to investigate/solve the issue?

alternatively, would it be possible to replace the cube with something else?
thanks for your help!