We need to change battery on Korg X5DR Can we do it ourselves and how?

The manual should be VERY close to that for your unit. I suspect the CR2032-HE2 is one of the cells that has stiff little legs (soldered in) that hold it slightly above the circuit board. You will likely have to make do using a tabbed version and a couple pieces of stiff wire. I could NOT find a source for the cell specified in the parts list. The X5D manual shows the battery position on the board. It should be the same for the R version. It is shown slightly left of center near the back wall of the case. Most of the service manuals are for different versions and the circuitry in a series pretty much is the same. The manual should be VERY close to that for your unit. I suspect the CR2032-HE2 is one of the cells that has stiff little legs (soldered in) that hold it slightly above the circuit board. You will likely have to make do using a tabbed version and a couple pieces of stiff wire. I could NOT find a source for the cell specified in the parts list. The X5D manual shows the battery position on the board. It should be the same for the R version. It is shown slightly left of center near the back wall of the case. Most of the service manuals are for different versions and the circuitry in a series pretty much is the same.

The R is for the Rack Mounted version... the circuitry will be nearly the same in the parts that count... just missing the keyboard panel scanning parts. They often make the boards fit both the Keyboard and Rack versions. They will use the same battery for sure. When unsoldering the battery and clearing the holes one can damage the board... You MIGHT want to evaluate whether you can cut the tabs of the old battery leaving the tabs in the board and solder the new tabs to the old... as it doesn't appear the HE2 tabbed cells are available easily. When cutting the tabs from the old battery use a flush cutter that doesn't apply much pressure during the cutting. Remember the circuit baord is sacred and the battery is expendable so the idea is to get the cell out with no board damage. It is OFTEN better to have just the leads even if you are removing the leads from the board instead of fighting removing the whole battery. The R is for the Rack Mounted version... the circuitry will be nearly the same in the parts that count... just missing the keyboard panel scanning parts. They often make the boards fit both the Keyboard and Rack versions. They will use the same battery for sure. When unsoldering the battery and clearing the holes one can damage the board... You MIGHT want to evaluate whether you can cut the tabs of the old battery leaving the tabs in the board and solder the new tabs to the old... as it doesn't appear the HE2 tabbed cells are available easily. When cutting the tabs from the old battery use a flush cutter that doesn't apply much pressure during the cutting. Remember the circuit baord is sacred and the battery is expendable so the idea is to get the cell out with no board damage. It is OFTEN better to have just the leads even if you are removing the leads from the board instead of fighting removing the whole battery.