Remove dash board to replace burnt light bulbs

That is an easy fix, it is one of two issues.
(1) Check the fuse for the dash lights. If the fuse is ok , it will be (2) burnt out bulbs. For #2 - you have to remove the bezel surrounding the dash cluster. Then look to see if the bulbs are good or have burnt out. The new bulbs are available at almost any auto parts store.

Do you have any mileage programmer, use the to reset the dash system.

The radios on older BMWs often have lighting issues where the display is dim or not functioning. To properly fix this, the radio needs to be removed. Open the hinged tabs that cover the bolts and use a small wrench to unbolt the radio. Remove the plastic cover and then pull off the top cover, usually held on with two screws. Remove the display circuit board and then the tape or CD player. This should reveal the main board. Check the bulbs to see if they are getting power. If they are not, they are burnt out. Replacing them is a little complicated but possible for a home mechanic
Read more: Troubleshooting a BMW Radio Display ' eHow.com http://www.ehow.com/way_5437656_troubleshooting-bmw-radio-display.html#ixzz1CNag2wjc

If they all stopped working at the same time then it is probably a fuse or possibly 2. Check your fuse panels in the dash and under the hood. The dash lights and gauges should be a fuse labeled instrument cluster or guages, it is probably blown. The other fuse to look for will be the tail light fuse. This is where I would begin.

Just remove the 4 screws and then slowly pull the cluster out and reach behind and disconnect the plugs on the back of the unit and then remove the cluster. The bulbs can be removed by turning them and pulling out.

replace relays and fuses for the power seat and windows.change dash light bulbs.if bulbs are good you got wiring problem check ground wires.

ON CERTAIN CARS YOU HAVE TO JUST REPLACE THE CLUSTER, THE EASY OPTION OF JUST REPLACING BULBS ISN'T ALWAYS AVAILABLE FOR ALL CARS

1st verify that the brake lights work, if not replace the burnt bulb, if they are ok then the warning module is defective.

The dash will have to come out for the A/C prob to check the stepper motors and wiring. There are about 6 motors back controling different flaps to control direction of airflow. Once you get the dash out, turn on the car and start working the climate control to see what motors and flap are doing what. Once you see what's happening or not happening, you will know what to do then. about 4 to 5 hrs to take out dash fix prob reinstall dash.
The dash does not have to come for bulbs. For the cluster, you may have to drop the wheel if it does not adjust down far enough to remove the cluster. Drop the lower dash under the wheel, one of the bolts is left hand thread to hold the wheel up, two wery small screw hold the cluster, it slides out. One hour at most; two if no experience doing it.