My car's meter is not showing seatbelt and door open sign.

Robert is on the right track here. Almost all cars on the road today do a bulb check when you first turn the key on, lighting up all the icons on the dash. So put the key in the ignition and turn it to the on position (no need to start it) as you keep an eye on the dash, particularly noting where the seatbelt and door symbols are.

If they light up during the bulb check, then you have something wrong with one or more of those systems; otherwise it's just a couple of burnt out bulbs that may or may not be a royal pain in the backside to replace.

Give that a try and let us know what you find!

Both bulbs should have the same PNC Reference number from Mitsubishi (81299B) which are also referenced as MR444536 a lot.

If it does end up being the bulbs I believe there should be two screws at the top of the gauge cluster you have to remove, which will let you pull the top piece of plastic out. There should then be 3 screws holding the gauge cluster in, gently pull the gauge cluster out to give yourself enough room to be able to unplug it from the back.

Replacing the bulbs is easier if you take the back panel off of the gauge cluster, which should only be 4 screws, and then at that point the bulbs that need replaced will be easier to access and should just be directly behind which ever indicator light is blown out.

There shouldn't be any specialty screws, I believe they are all Phillips head, and as long as nothing gives you trouble it should only take about 20-30 minutes.

Hope this helps!

(Also great advice on how to diagnose if the bulbs are the issue or not, thanks Jerry!)