there are batches of psbreak and usbbreak, which is using 18F2450 16KB chip.
The pcb is designed for 2455/2550 using usb hid bootloader, unfortunately,
18F2450 doesn't have enough space to hold both the firmware and the hid bootloader. So they just flash the firmware only, leave it not upgradable via usb. The button of course won't work, some pcb even doesn't have the button soldered.
Also to hide all the mess, they polished the chip top side to hide what chip it is.
If and only if you have a PIC programmer and have experience doing such things, you can wire the icsp programming interface and refresh it.
If the chip is 2450, it can only hold PICDEM bootloader;
2455/2550 can hold USB HID bootload.
You may need to build a switch/jumper for the upgrade mode.
I don't have one of these so I can't say more detail on this. If you successfully fixed it, you can post your work here and the others could benefit from it.
Note: for people who has a not upgradeable ATmega16* chip, this page may help