Lighting niche- Screw broke off- What now?

[WannaPool]

So in an attempt to find a leak today, I removed my Pentair light from the niche. Then I spent about 30 minutes trying to get the light back in the niche.... While this is always a PITA for me, today was even more of a PITA.

The machine screw (on the top) that holds the light into place would not catch the threads in the hole. Closer inspection revealed there is a piece of the machine screw stuck in the threaded hole. It must have broken off while removing the screw. There is nothing on either side to grab to try to remove. Normally I would just drill out.... but I don't have an underwater drill.

Any suggestions?

 

[WannaPool]

... now I am confused.... I have one of these attached to the bolt:

Swimming Pool Light Wedge Repair Tool Replaces Broken Screw, Niche Tab Part 132 | eBay

SWIMMING POOL LIGHT WEDGE TOOL REPAIRS BROKEN SCREW NICHE RING TAB. The “light wedge” is an adjustable plastic wedge and stainless steel screw that goes through the light ring. After the bottom of the fixture catches on the niches bottom the fixture should be tilted up until the fixture is flush...

www.ebay.com

I wonder of the screw was ever screwed in to begin with.... The ring around the light is new. I installed it a few years ago but I do not remember the hole being blocked.
(The original ring corroded really bad).