I have some of the keys on my n900 not working. Specifically the 3 left keys (ctrl, fns, shft), T, down arrow and right arrow. I disassembled and cleaned keyboard but it didn't help. Anyone with a fix for this? I bought it off eBay, can I return it to Nokia for repairs?
Thanks!

as you have opened it your self, so nokia wont repair it!
you can try but i doubt they will repiar. In England N900 has 2 years warranty. so you can try, may be

Does it? I live in England and I bought my N900 second hand and it's USB port just broke (a couple of days ago), so I checked the Nokia website and put in the IMEI number on the box into their warranty checker then it came back with something like "Based on the date of manufacture the warranty has expired but if you have proof of purchase that you bought it in the last year you should still be able to get it repaired", then I thought "oh bugger, but at least the guy I bought it from included the receipt, so I might be still be able to get it fixed, so I checked the receipt and noticed it had the IMEI number written on it and it didn't match what was on the box and thought "oh sh*t! the guy I bought it off has pulled a fast one on me and given me an N900 that was older than he claimed it was", then I noticed that the IMEI on the receipt did actually match the phone, so I put that IMEI number into Nokia's warranty checker and that came back as being in warranty and I was much relieved, so now I've taken it into a Nokia care centre and it has been sent back to Nokia for repair without any hassle, and hopefully they'll actually fix it.

The points I wanted to make from my tale were, Nokia doesn't seem to have an official 2 year warranty for the UK (but you might have some luck taking back to the retailer you bought it from under the "sale of goods act" in this time frame). And you can check if your N900 is still under warranty on Nokia's site and if that says it is you can have them collect it, or take it into one of their care centres for a (relatively) hassle free warranty repair and you should be able to do it without a receipt.

If you were careful when you opened it you might still have some luck with the warranty route, but if you left any obvious signs that you opened it yourself, it may be a bit iffy.

Hmm, I got my first luck. It says my unit is still under warranty according to their site. I'll call them tomorrow to know where to ship it to and hopefully they will accept an eBay/paypal receipt. For the opening, I thought it was going to be simple cleanup to fix it. Well, 2 screws are slacked but I'll try my luck anyway.

I believe the UK consumer law is such that items that fail within a "reasonable life expectancy period" is still liable for warranty repair or replacement. So even if manufacturers only officially give a 1 year warranty you can still "force" them to repair/replace outside that period. For a device like the N900 to fail within 2 years is IMO not reasonable.

That's the Sale of Goods Act. The agreement is between the buyer and seller, if the item is faulty it is the retailer that is responsible for the repair or replacement, not the manufacturer, but this law also applies between the retailer and their wholesaler (and all the way up the chain), but once you take it back to the shop you bought it from it is their responsibility to sort out the problem. You cannot however demand this directly from the manufacturer unless you bought it directly from them.

They might notice the screws, the service manual says to discard the screws when taking it apart and use new ones for putting it back together. I guess it'll depend on their policy and how carefully they check these things.

True, I used manufacturer in my post because in most cases the faulty goods will ultimately be the manufacturer's responsibility. The important point is:

Ultimately, yes they usually are, but if they aren't interested the consumer has to get the retailer to sort it out.

The caveat is that this only applies if it is reasonable to expect the item to last that long. I wouldn't say it was reasonable to expect a mobile phone to last 6 years (although they often do), but it is reasonable to expect 2 or 3 years from one as long as it isn't mistreated.

My oldest phone is 15 years and it still works although the battery barely holds a charge. My next 2 oldest are both more than 10 years and still work fine. So in my experience I would say it's more than reasonable to expect a phone to last 5-6 years. But getting back on topic, an N900 dying within 2 years is completely unreasonable.