Did you make any progress with this? Good information above. If you're new to how lights work and understanding what's going on, the ol' wiki might help a little. Here's the link to the kind of perfunctory troubleshooting page but it has a couple of helpful links to forum posts (I can't get the old CPF links to work for me but the "Dan's" BLF post is still here...scroll down a bit on that one).
Wiki: https://www.aliexpress.com/item/4001237268675.html
Dan's post from 2010: https://budgetlightforum.com/t/-/250
I assume you've already done the most basic thing in cleaning the threads and bare metal contact surfaces? Often just old oxidized lube or the "wrong" lube can cause intermittent connections, or maybe some debris in there. Switches do fail, especially cheapies, so that's always a likely candidate and Hank's description above is an easy test to try and pinpoint that. Other things in the head/driver take more exploration but sometimes easy things to spot like poor soldering or solder spatter, etc. will be a quick fix, if the light is easy to disassemble.
If all that is too much trouble there are definitely some much better zoomies these days. I'm not a zoomie person so I don't own any of these but this one from Simon has been well received in reviews (he has a couple other options in his store in the "Z" series, but this basic one without battery still lets you pick emitters and such). I think Lumintop and Sofirn have also had some out if I'm not mistaken...surely several others that are not the old low-end copies. Some of these are probably on amazon, too, if you don't want to wait for china shipping.
https://www.aliexpress.com/item/4001237268675.html