Similar problem - not seen any definite search results with solutions for people with this issue - I replaced the battery on our 2018 CX-5 and used a Schumacher SEC-12V battery saver that plugs into the OBD2 port as I was afraid of losing a myriad of settings in the CMU, lights, windows, etc. - then later after the swap my wife noticed the CEL was on and I went to plug in both of my OBD2 scanners and neither powered up. I also noticed the auto up power windows weren't working, so the memory saver didn't work. All this leads me to believe a fuse might be blown, perhaps by my memory saver. At least I hope that's all it is. I've printed out the fuse diagram and I'm looking forward to a an hour of probing (once I confirm no power on the OBD2 port itself using a multimeter). I'll post with results, good or bad or null. This much I can tell you, it's not F54 Room fuse under the hood - nor I believe any of the underhood fuses - they all tested ok with a test light.