Batboard

Hello, I have recently acquired an MTX 838 (136-178mhz) with 6 digit display with 99 channels and continuous rotary dial. The radio works great...if you boot it up cold. It will continue to work till you power cycle the radio. Once the radio has been on and had a chance to "warm up" it will come up with F01/81(External ROM/Flash checksum error). If I let the radio sit and cool down (or accelerate the process with external cold) It will boot up again no problem and continue to function till rebooted. Is there something that can be done to remedy this or am I stuck looking for a new control board? I swapped control boards from an MTX838 with 16 channel capacity and no display but you lose all the fancy functions like display and 99 channel.

Thanks for any help.