How To Clean A BenQ DW1620?

Has anyone here opened up their BenQ DW1620 or rebadge and cleaned the lens or other components? If so, what type of tool did you use to remove the inside cover? Unlike the DW1640 and DW1650, where removing the outer drive cover makes the lens accessible, with the 1620 you have an additional barrier that must be removed with a special tool, and I’m not sure if it’s an allen/hex wrench, and if it is, what exact size it is.

I’ve never opened my 1620’s that I can remember though one is now dead so I may try it sometime myself.
Usually when manufacturers try to get tricky they use security bits that usually are like regular hex nuts with extra pins and things in them so a regular socket or tool will not fit. Motorola used to do that with their cable boxes and many others do too. If it’s a normal type of security thing there are sockets kits available that have most or all of the common ones. I bought a set at Harbor Freight tools and I’ve seen other better quality ones for sale lately though the one I got is fine for the few times I’ll use it and was cheap.