I think you'll have to be the pioneer on this one.
I worry about the same thing occasionally.
Mine has been in use since about 2002 and has been used for about 600k miles of driving on different trucks. It still works like new but I occasionally think about it failing. It is one of the best pieces of automotive equipment I have ever purchased and used.
I don't know if the digital display is repairable. If mine failed I would try a small, old fashioned electronics shop where someone repairs CB radios, scanners, old tube radios, basically old fashioned electronics equipment. The old guys that do that are genuine electronics technicians and know how to diagnose problems and replace parts.
A MaxBrake available from Southwest Wheel is functionally the same although it does not have the nice digital display or as many adjustments as the BrakeSmart.
If you are unable to have it repaired and decide to replace it please let me know. I'll buy it from you to keep as a spare for the other internal parts.