Omnitik 5 AC will not power when ether2 is connected.

Hardware MikroTik hardware general
1

I have noticed a very odd behaviour with an Omnitik 5 AC (RouterBOARD OmniTIK G-5HacD).
After power failure the Omnitik will not power on (no lights) if the cable is left in ether2.
If the cable is removed from ether2, the unit will power on, and once it is on the cable can be connected back in without problem.
This Omnitik is not POE model, so it does not have POE out.

The cable goes into an injector that feeds an ISP provided SXT5 (or similar, can’t remember exact model).

This setup worked fine for couple of years, until recently after power failures it started to misbehave.

I am not at the location, next time I am there I will try different port and see if it replicates the issue.

Can the injector back-feed the other end and thus causing power up to fail?

2

Update:
I tried different ports, and all other ports exhibited this issue.
I tired different injector upstream and issue was still there.
I opened up the device (BTW there are two hidden torx screws behind the feet) and there were no water or fauna ingress.
I switched the PoE from an PoE switch (which had no issues powering the device for many years) to an injector and I can no longer reproduce the issue.

I guess I will have to put up with wall warts.