Xbox One Controller - Model 1537 Torx T6 does not fit

I was asked by my friend to clean his Xbox One controllers. He’s got two controllers included with console, and one controller bought later. They got dirty during years of operation.

I wanted to clean underside of buttons, but I found a problem – I cannot undo the screws on the motherboard!
All the pages about disassembling Xbox One controllers say you need Torx T8 security for the outside screws (that’s true) and T6 for the motherboard.
I cannot undo the screws on the motherboard, therefore I cannot get under the buttons to clean them.
Looks like T8 is too big and T6 has got some slack, so maybe I need T7 to remove those screws? (Pic related)

I just read, that I’ve got two controller models.
Model 1708 was easy to disassemble – just like in all online tutorials.
Model 1537 just cannot be disassembled using T6 screwdriver.

Does T7 fit on model 1537? Or is there other way to remove those screws?