HP PageWide Enterprise Color 556

4. Release the bosses along the right and left side of the cover, and then lift it straight up to remove it.
Figure 1-132 Remove the rear cover
1
2
1
2
Step 4: Unpack the replacement assembly
1. Dispose of the defective part.
NOTE: HP recommends responsible disposal of the defective part.
http://www8.hp.com/us/en/hp-information/environment/product-recycling.html
118 Chapter 1 Removal and replacement ENWW