So there is something else to look into.

What type of LED tube did they use?
What type of ballast were the old fluorescent tube fixture using?

If the LED tubes are of the type that requires the electronic ballast, are the fixtures using the electronic or magnetic?

I can only assume if the LED tubes require the ballast, magnetic or electronic, to be removed. That the LED tubes either won't work, or would've blown up on first switch on.

KOT