Even tho this thread is now long silent, in the event that someone is reading this, if you look at the very first post in this thread, the user wrote that the desired version of the OS is in fact 840EX, not 840.
The OS version on the Roland site for the EX is 2.05, so the upgrade as outlined can still be accomplished (assuming same hardware parts are available.)
Edited by MScott906 (03/17/22 04:45 PM)
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VS-2480, VS-2400CD, MV8000 w/ MV8-OP1, XV-5080, S-550, MC-909, V-Synth, Fantom 6S, Akai Renaissance MPC