I think you only have a couple of choices.
1. Contact the vendor to see if you can get a replacement.
2. Take it apart and replace the 510 connector.
Try the first, it may work. The second could be difficult but may work.
I believe the 510
threads are press fit into the top cap. You would need to drive or drill that part out and replace it with a different 510 connector. The
threads on a 50w are stainless steel so drilling might not work.
I successfully replaced a 510 connector in a 20w
istick with one of these.
510 SEALED Battery Connector DIY Mod apv Parts Lot Discounts US Seller | eBay If I was to do it again, I would buy some of these instead
510 Battery Connector SEALED 18AWG Prewired Stainless Steel DIY Mod apv Part Lot | eBay since they are SS. The center pins are not spring loaded so you might have some connectivity problems.
I had to drill out the threads with an11/32 drill bit and cut the bottom "skirt" off the 510 connector with a Dremel to get it to fit. Then solder the connections.
Someone here made a replacement top cap that was thicker and used a Fat Daddy's Vapes 510 connector that is SS and has a spring loaded center pin.
Fat Daddy Vapes 510 Connector V3 | Sun-Vapers San Diego
Good luck!