We need to get access to the Z88's main board, so it must be completely disassembled. This requires the removal of eleven cross point screws in the base of the case. Most are easily visible, but two are beneath the rubber front feet, which must be carefully peeled off, whilst another two are under the pull out support flap. The left one of these is probably hidden under the edge of the serial number label, which can just be bent back enough to release the screw. All of these are highlighted in the following picture.
Now the keyboard must be removed and again care must be taken in gently pulling out it's two ribbon connectors.
Ease the two battery springs from off their mounting, and slip the 9 pin D socket out of it's recess, and then the main board should just pull over its mounting pillars and come out as a single unit. Handle it carefully, static isn't a real problem with the whole unit, but you should avoid touching any of the exposed contacts, particularly for the expansion slots, as these can be easily oxidised by sweaty finger contact, and made less reliable.
