I have just opened my Humax RM-F01, cleaned the keypad and re-assembled it.
I first removed the batteries for safety. The top and bottom are totally separate (no wires) when they come apart. There were no screws holding this remote together
I inserted the tip of the small blade of a Swiss Army Knife into the seam that runs all around the remote 3mm from the top. I started about 90mm from the IR transmitter (between two lugs) and gently eased along the seam towards the middle of the remote, pushing out the side slightly and levering up the top, until the first lug popped out of its slot halfway along. I then carried on with this technique until all 14 lugs were popped. I found it easier to pop the end lugs after all the side lugs were freed. None broke and very little force was needed. The lugs are symmetrical each side and are positioned as follows starting from the IR end (top): 20mm, 65mm, 115mm (centre), 165mm and 210mm - each measurement to approximately the centre of the lug. There are two lugs on the bottom 15mm from each corner and two at the IR end 10mm from each corner.
Once all the lugs were popped the keyboard complete with circuit-board lifts off the housing and there are no connecting wires. To remove the circuit board there are 4 plastic lugs. I eased the board from underneath the bottom two (one at a time) and it came easily away from the top two. The buttons are all on a single rubber sheet which lifts off and can be cleaned by washing in warm water with a drop of fairy liquid. Rinse thoroughly in clean water (preferably de-ionised) and thoroughly dry before re-assembly. Ensure the loop of springy wire connecting the batteries is still in place in the housing before re-assembly. It is easier to engage the top and bottom lugs before the side lugs are clipped as there is more give in the sides.
The RM-F01 is supplied with the Humax FoxSat-HDR Freesat+ recorder. This technique also works with the Humax RM-F04 remote control that is supplied with the HDR-Fox T2 Freeview+ recorder.