Hello!

A few weeks ago I bought a new front-cover for my N900 on eBay, because the touchscreen was damaged.
I brought my N900 to a repair shop and wanted them to change the front cover because I don't have the tools and knowledge to change it on my own.
They said that they can give no warranty, because it's my own front-cover I bought on eBay. I agreed and the built it in.
After that i was shocked because it looked horrible. It was no original front-cover as the eBay-Shop told me, it was a very very bad copy that didn't really fit to the n900, but the repair shop changed it anyway.
After calling the eBay Shop they told me to send them my N900 and they would change the cover to an original Nokia-Cover (as they sold it in their eBay Shop). I sent them my N900 and they sent it back with another cover, that fitted and looked much better than the other one but was still no Original in my opinion.

Now after all I recognized that the keyboard-illumination doesn't work anymore and the phone doesn't unlock when I open the keyboard, so I think the sensor which recognizes if the keyboard is opened or closed, is broken.

The eBay shop says it's the fault of the repair-shop which changed the cover first. The repair shop doesn't want to repair it because they say it was my own risk.

So what can I do now? Is there any way to fix my problems without paying a lot of money?

I just installed the app "BootMenu" but the program only works if the keyboard is open so I can't start it.

I had this problem when I changed my N900 housing.There is tiny magnet that sits in the screen housing unit - the new casing I bought did not have this, so I had to use magnet from old screen housing.

see the following thread for images showing the location of the sensor and magnet: http://talk.maemo.org/showthread.php?t=64949

those keyboard lights wont be damages easly just by changing the cover...
i believe your motherboard have been changes to a semi faulty one...you should check the device IMEI just to make sure is the same like you buy at first place....