EcoRenovator - Split air handlers fuses blown

Hello All! I successfully installed a split air system in my home about 5 years ago with help from this forum, and have been enjoying it every year as it gets warmer and warmed in the Pacific NW. I have three indoor air handlers: a 18k BTU ceiling cassette type, and two wall mounted units, one with 12k and the other with 9k. Last used the system in late September last year, had some warm weather a few weeks ago so turned on the ceiling unit, it started up and worked perfectly. (As did the outdoor unit). I then went to fire up the two others, both dead a a door nail. Checked incoming power on each, present on both. Then extracted the control boards (no easy task) to discover the single fuse on both boards were blown. Replaced the fuses, checked for continuity, and reassembled, still completely dead, tho the new fuses did not blow. I have ordered two new control boards but am leary of just installing them without getting some feed back from folks here. We're not prone to power surges in my area and I find it really odd that this happened to two of the three units and while the units were turned off sometime during the winter. Could some other component within the air handler, other than the circuit board, have caused this and might fry the new boards I install? Sorry for the long read, and I would sincerely appreciate any and all thoughts.