I cant imagine why someone would go to that trouble (referencing the video posted above). When the lock cylinder fails, you need a new one. Band-aids like graphite, oil or hammer taps will only buy you some time- it will still fail and leave you stranded at some point in the near future. I would not recommend a used lock cylinder – you’re then facing the same problem again, within an unknown timeframe. When buying new, you have two choices- new lock cylinder with generic key and no coding (as shown in the video) or new lock from Volvo with lock cylinder cut for your key, and chip coded for your fob, based on your VIN. The difference in cost is minimal, and you’ll spend more than that difference getting your keys swapped, and/or having a dealer flash the chip code.
I bought a new lock cylinder from a Volvo dealer online- it was cut and coded for my VIN, and the part was plug-and-play. No visit to a dealer, no key cutting/swapping, no code flashing. Took a couple hours to swap the part out. It was even easier than the write-up I posted (a few posts up). On the XC90, you do NOT need to remove the steering wheel or airbag. In fact, you may not even need to remove the stalk switches (I did though, it they were very easy, 2 minutes each, tops). Basically, you just remove the upper and lower steering column cover (Torx T-25 i think, 3 screws), remove the two main stalk switches (small phillips screws, may be optional), then get your drill. The two bolts are shear bolts, and the head shears off when proper torque is hit. This leaves a round metal dome, which must be removed. Drilling is probably easiest, but access is tight (mostly due to the odd angle you’re drilling at). And the drill bit wants to walk off the metal dome. Its not easy, but patience and a few tips will help. First I tried starting with much smaller drill bits, like 1/8, 3/16, 1/4, 5/16, any of the above, and working your way up to 3/8 in several increments, so you have a smaller “pilot” hole to prevent the bit from walking. Then I tried using a cutoff wheel on a dremel, not to cut the bolt head off (angles dont quite work perfectly, but i suppose possible), using the cutoff wheel perpendicularly to cut away the top of the dome, and make it concave rather than convex. This kept the drill bit perfectly aligned. Once free, its an easy matter to swap lock cylinders, first swapping the bezel on the front (around the key hole) and the ignition module (round black plastic piece) on the rear. Reinstall lock cylinder, stalk switches, and column covers.
Not a bad job, really. Took me 3 hours, but 2 of those were figuring out how best to drill the bolts out.