You need a phillips screw driver, a 7 mm socket and a soldering iron with a small tip. No solder will likely be needed.
Research here and elsewhere showed that the instrument cluster lights on my 2007 QX56 were led lights soldered on a circuit board inside the cluster. No bulbs to simply replace. Alternatives to doing it the way I did were sending the instrument panel away for repair for $150-ish (this is my only car so that wouldn't work) or get a used instrument cluster for ~$200, not knowing if it had issues (apparently these instrument cluster are known for this problem circuit problems of all kinds). I could have also taken it to the dealer with a cost of $500+ for the cluster and unknown labor charges.
I couldn't really loose my truck so I took a chance have done soldering over the years with a few successes so I did it myself. The difficulty level was pretty low but I have removed the instrument clusters in other cars before and have soldered various things several times before. In all would take about an hour.
The leds are surface soldered to a circuit board in the instrument cluster. (See image 1) But for me a bad led wasn't the issue. It was most likely a "cold solder" on the back side of the circuit board on one of three small components in the air bag light circuit. Cold solder basically means the solder was not applied well and broke free or may have cracked interrupting the lights circuit. To diagnose this, you'll take out the instrument cluster, remove the circuit board, plug the circuit board back into the dash plug and turn the ignition to on but no need to start the truck.
Here's the process.
1. Remove the instrument cluster from the dash. There are youtube videos on how to do this.
2. Once out, remove the front cover and back cover. Just held buy little tabs around the edges.
3. Remove the gauge pointers (hands of the speedometer, tachometer, fuel level and engine temp). They pop off. note their general off position. Once removed, the circuit board (See image 1) will be free.
4. To test the issue, place the circuit board back in the dash and plug it in. Turn the key to power on (no need to start the truck). For the first 7 seconds or so the lights and systems will self check, lighting up as they do so. ID your light and see if its working. Probably isn't of course.
5. Turn the key off and back on to rerun the self-tests this time pushing firmly on your light and see if it turns on. Note in my case, It helped if I held the corner of the circuit board and then pushed on the light. If you can get your light to turn on this solution might be for you.
6. Assuming your light turned on in step 5, heat up your soldering iron. I used a small inexpensive iron I got at Harbor Freight for like $4 a while back. Couple warnings. Too much heat will destroy the led light which from what I gather is hard to find. the goal is to just re-melt the solder at each point the component is soldered to the circuit board. I did not need to add solder. I tried heating up the 4 contacts on the led light itself with no luck. I also heating the solder points on a nearby component but it didn't help either. (See image 2) In the end I found three components located generally near my light but on the back side of the circuit board. (See image 3) I heated up the solder points of all three and that fixed the problem. Now if this doesn't work for you, try resoldering other components near your light or on the back side of your light.
After that, I tested my repair and when it worked reassembled in reverse order and passed reinspection.
IMAGE 1 - QX56 instrument cluster circuit board
IMAGE 2 - QX56 instrument cluster (Air Bag Warning Light (Circle) and related component (rectangle)
IMAGE 3 - QX56 instrument cluster back side (Air Bag Warning Light related components (circle)
