Great Puma (Level 12)
Search eBay for a 3.8mm gamebit, this will remove the screws you see on the TG-16. NES, SNES and Gameboy cartridges also use these screws. You may as well get a 4.5mm gamebit while you're at it and save on shipping if the seller offers both, for Genesis cartridges, SNES and Gamecube consoles.
However, be aware that once you get the TG-16 shell off you'll have to desolder the RF shielding from the main board, and it's not the easiest system to diagnose and repair. Most of the components are proprietary.
Unless it's an issue where the system's not turning on (blown fuse) or your RF video port is being flakey you're probably better off getting another system.
Insert Coin (Level 0)
Yeah, the system isnt turning on, im not getting any power at all.