Just don't do it! The components cost about 25,- US$ but the damage you can do to the box can make it a total write off!
Even worse is the idea to convert a DM5620 to a DM7000
The CPUs are different
- DM7000 uses a IBM "Pallas"
- DM5620 uses a IBM "Vulcan"
Yes they are same speed and specs but the Pallas has the IDE port on board!