How to remove cover on fujitsu split system head

To learn more about your unit first see whether the unit is receiving power. Check to see your breaker is turned on and that there is power coming out of the breaker (use a volt/ohm meter and measure for 115 volts or 220 volts depending on the units requirements.) Fujitsu has code lights that light up to tell you the status of the unit and gives error codes. I assume the unit is dead and there status lights are not lit up.

Next check for power at the outdoor unit with the volt/ohm meter. The outdoor unit will hav a disconnect box on the wall. Some have fuses which may be blown, some have breakers, and some have no fuses or breakers but do have a shorting bar with a handle that you pull straight out to disconnect power going to the outdoor unit. Once you have opened the cover of the unit you can tell which kind of disconnect you have. Remove the cover or pull the disconnect bar. You then will have the power circuits exposed and can measure to see if the unit is getting power.

Next, in the case of mini splits, there is sometime a indoor power switch to disconnect power to the indoor unit. The power for it comes from the outdoor unit. Make sure it is turned on. Sometimes kids play around and throw switches and don't know what they are doing and kill the power to the indoor part of your unit. If you are unsure if the indoor unit is getting power, you can remove the indoor cover by prying off the cover, then unscrew the phillips screw on the right of the panel to expose the incoming power terminals and measure for power actually being at the unit.

Lastly if you have power to the outdoor unit but no power to the indoor unit and there is no problem with the indoor disconnect, go back to the outdoor unit and check the fuses to see if any are blown. They are located inside the outdoor unit. You will have to remove the outdoor cover and screens to get to them. At this point you should have a repair manual with information on where the fuses are.
You may be getting over your head at this point and will best need to get a repair person with experience.

Most people are not capable of doing his last step.

First remove the filter cover by lifting it up then sliding down the retaining tabs on each side next to the hinges. Next pull out the filters. Then remove the screws from the front panel remembering that there is one screw behind the terminal cover. Then you need to use a flat blade screwdriver to lift the three clips holding the top rear of the cover to the rest of the casing at the left, middle and right (see photo) then pull the cover forward. I'm not certain but from memory, you might have to unhook the head unit from the bottom of the backing plate for this to come off. Be careful you don't break the cover while doing this. You may need to get a ladder to see the top clips.

open up the front cover as if removing the filters
along the bottom of the main cover you will find 3 screws
undo then , lift forward and up with the main cover and it separates from the fixed unit on the wall
that is all you can remove as the main unit is fixed with the popes and drain on place

The unit pivots from the top much like a Honeywell t-stat it snaps into place at the bottom in two places approximately 1/3 the width of the unit in from either side. It is mounted to a flat plate that is secured to the wall. The cover should be held on by screws. So no real pressure should be required.

I assume you have a split system? If so, the rear channel is usually moulded as part of the indoor unit assy. The front drain is removable but the back isnt. Not much can go wrong with the rear drain. On rare occasions, mice etc build nests at the back which block the drain and then you get water leaks when using the machine.

What type of system is it? What application (ie) window unit, split system?

Better to pump down the system and remove the indoor unit completely. You can't remove complete cover.And also your painting spray will block indoor coil.

THE INTAKE GRILLE REMOVAL
(1) Open the intake grille.
(2) Pull down the knob.
(3) Lift the intake grille upward, until the axle at the top of the intake
grille is removed.

THE FRONT PANEL REMOVAL
(1) Remove intake grille (Reference the intake grille removal.)
(2) Remove four screws.
(3) The thumb is hung on the lower part as shown in the figure,
and it pulls to the front, pushing [-] mark , and bottom hooks
(two position) is removed from wall hook bracket.
(4) The front panel bottom is pulled to the front, and bottom hooks
is removed indoor unit.
(5) The front panel is pulled to the front, raising the upper surface,
and a front panel is removed.

Ok, there are a few things to check.
1. Batteries on the remote.
2. Reset remote - switch sometimes in battery compartment and sometimes behind cover, need to press with sharp nib or pen.
3. Check on indoor unit that remote has been selected on the manual/auto switch, located under the cover on right hand side.
4. Remove indoor unit cover complete, (three screws behind the louvers and one on the electrical cover). Change the remote sensor board.

try, http://www.uelements.com/downloads/Fj-aby14rga-sm.pdf