I don't know if they are identcal, but the M90 and M92 screens are both listed by Onyx as being "Display Type: 9.7" E Ink® Vizplex® PEARL EPD display"
Onyx USA has M90 repair screen kits available due to a defect in some production runs. See here for details:
http://www.onyxboox.com/product_info.php?products_id=40
Emailing Mike Hu (USA distributor) might give you more info than I can give you. But Booxtor is right: it matters from whom you bought the device. They should be your primary source of info as to what options you have.