To jake brake:
Solenoids are sometimes activated by stray electromagnetic fields
as you suggest. A Shorts 3-30 fell on its "knees" when an errant field
pulled the gear pins, while pax were unloading. Perhaps it happened more
often.
Inadvertent in-flight liftdumper deployment on a Fokker 100 comes to mind from several years ago. The cause was determined to be the combination of EMI from a faulty Flight Control Computer on a wheel speed signal, a skid control box power-up spike on landing gear DOWN selection, and liftdumper arming before landing gear extension.
Ref. sources below:
http://www.federalregistersearch.com...3062-filed.asp
http://www.federalregistersearch.com...9512-filed.asp
Green-dot