We makes train parts. When I first started we were a division of an avionics co., so I know many of the safety requirements are similar and the basic system is nearly identical.
The system is very tight for new builds and this would be impossible. However, for replacement parts, less so if somebody is willing to commit fraud. But such parts are only supposed to come from a certified supplier. If the buyers followed the rules, no way could a fake company get certified.

https://www.breitbart.com/pre-viral/2023/10/05/airplanes-grounded-over-concerns-that-parts-were-sold-with-fake-safety-certificates/