You don't need to remove all the screws at all - I removed just the hd/memory lid screw and another for the cd/dvd drive. I just replaced my P855-S5200 keyboard last night. Apologies for no pics .... it never occurred for me to do it at the time!
- Take the battery out and disconnect the power supply out first - good standard practice
- Remove the lid for the HDD/RAM etc as mentioned (there might be a rubber grommit covering the whole for the screw)
- there is a screw holding in the CD/DVD drive ... it is labeled as either F6 or F3 .... located just to the left of the RAM slots. If you can't find the screw, go onto youtube and do a search for remove toshiba ODD drive - Toshiba support have a load of videos there (strangely, nothing for keyboards)
- remove cd/dvd drive
- you can now see a small rectangular cut out from the chassis (somewhere near the left CAPS LOCK and SHIFT keys), revealing the underside of the keyboard.
- There are a series of wedges along the top, bottom and sides of the keyboard to hold it in place within the frame/chassis.
- From the chassis cut-out section, push the keyboard up (it's very flexible), concentrating on the lower left first and left wedges first
- progress from lower left to lower right wedges then the right hand wedges in turn.
- the top wedges should not present much resistance at all.
- the keyboard should now lift out ok revealing the ribbon cable
- Under no circumstances be tempted to simply pull the cable from the PCB connection -- it looks really flimsy. Instead you will see a clip at each side of the connector - use a pair tweezers to push the clips back towards the screen.
- Carefully remove the ribbon cable .... the keyboard is now totally disconnected.
- Seat the ribbon cable for the new keyboard carefully into the connector - make sure it goes in straight and even until you can feel it touch the bottom of the connector
- Keep hold of the cable, making sure it does move, and with the other hand push each clip on either side of the connector back into position. This is a bit fiddly and I had to do it in two or three stages, alternating between each clip. If you push each clip down the whole way in one go, the other clip seemed to pop back!
- Seat the keyboard back into the wedges, working from top left thru top right, then the wedges on the right side, followed by bottom right to bottom left and then finally the left wedges.
- take a check to ensure that you have not missed any wedges - the keyboard should be sitting flush in the enclosure/chassis
- Place the CD/DVD drive back into the chassis and fix the screw back into position.
- put the lid for the HD/memory etc back into place.
- Put the battery back in, power up the device and try out the keys!
Hope this helps.