Replaced Gimbal, still not initializing, calibrating moving. Bad board?

[GeorgeVandalay]

I'm impressed with the many skilled folks on this forum. I have two MA2s, a "good" one and a "parts" one. Recently, the gimbal on the "good" one did not initialize and listed the gimbal calibration error. Camera feed is fine, gimbal moves freely. I swapped the gimbals on the two drones and the "good" drone still has the error while the "parts" drone works fine with the newly swapped gimbal. In other words, I have confirmed both "good" and "parts" gimbal assemblies and cables are functioning properly. Is it safe to assume the board on the "good" drone is bad? Is there any DIY solution to trouble shoot the board? Python service tools? Love to hear your experiences.