It's easy procedure to upgrade my rev6 A2000 to 3.1 rom?
Depends. It's a socketed chip, but the rectangular (DIL) kind. Aim for the gap between the socket and the bottom of the chip.
Levering either end, gently, alternately, a little bit at a time, it should just pop out. There are plastic tools to do this, but a small flat bladed screwdriver will do the job.
Plugging in a new ROM chip (only one on an A2000) is easy, just make sure you get the notch at one end the right way. Same way as the old one was.
Make sure it goes in flat, no bent pins. If one side is a little bit off, you can put one side in a little, bend the pins in a row to line up the other set, and press it in fully.
If you do bend a pin, it can be straightened out with small pliers - again, gently.
First time it's a big deal, but it's not that difficult really. Even if you never done electronics at all.