I’ve also come across references saying it’s interchangeable for movement 4U13 (which is apparently an older one, although both now obsolete).
The 4U13 uses a 321/SR616SW battery, same height but smaller diameter.
Might be able to do it with a rubber ball, depends how tight it’s on there vs how strong a grip the ball can get. Professionally, this would be done with something like https://www.cousinsuk.com/product/rolex-dies-6-with-wrench
Failing that, it’s the same type of back as Rolex, so look up how to open Rolex style case backs for other ideas.
And stupid question, have you checked it’s not a snap on pretending to be a screw on?
I’d definitely suggest a Lorus
https://www.loruswatches.com/Products/Kids
Stand up to a decent amount of daily wear, pricewise definitely in the “doesn’t matter too much if lost/broken” which you’ve got to consider with kids.
And until I checked just now, I didn’t realise how much of a range they actually have for kids watches.
TBH I’ve never even thought about it since the last time I was poking around inside a “traditional” tower unit switching out a 20GB harddrive for a 40GB one… yeah, at least a decade and a half ago.
Have done numerous other things since then that I *should* have technically grounded myself for - laptop repairs/RAM upgrades, mobile phone repairs etc… but completely slipped my mind and no resulting boom/zap/magic smoke so I guess it’s no big deal. The way I figure it, a lot of devices are made to be portable these days, and they’re bound to pick up static from simply being handled - how many times a day do you take your mobile phone in and out of pockets, tap the screen after walking on carpet etc?
To be fair even back in the day (and we’re going even further back in time here…) how many people would change a game cartridge in a SNES or Mega Drive and not even cast a thought to touching the bare edge connector of the PCB inside while doing so? Let alone blowing on them when they didn’t load, which only later in life did we get told this was a cause of corrosion.