Please see and follow the “Caution” here on this “Motif-Rack ES OS Updater V1.0.3”
Motif-Rack ES OS Updater Caution

Please see and follow the “Caution” here on this “Motif-Rack ES OS Updater V1.0.3”
Motif-Rack ES OS Updater Caution

Well, it turns out that I did the update to 1.03 and it does not start
It stays on the Yamaha screen.
I have looked at the yamaha service manual and it says that if that happens it is because the IC33 which is the flash rom could fail.
But I think that reinstalling a backup type system could solve the problem.

Well I did various tests.
I even tried the version of the old motif rack before the ES and that one made it go past that screen.
But it stayed on another frozen screen because it detected that it was another Synth.
The way to do resets and put it into service mode is impossible since I cannot access the system.
performing the key sequence to perform the update becomes responsive.

...
The unit may become inoperable if the electrical supply is interrupted while running the updater (by pulling out the AC cord, etc.). If this happens, run the updater again from the first step.

- If the unit does not function after running the updater, please contact your nearest Yamaha service center.
Yamaha Global Directory

- This updater is to be used at the user's own risk.

The Motif-Rack, Motif-Rack ES and the Motif-Rack XS are three completely different products. Firmware is not interchangeable AT ALL.
Trying another product’s firmware is completely wrong, and a waste of time and effort.

You want to find the OS Updater for the Motif-Rack ES, specifically.

Contact your nearest service center.

Does anyone have a backup?
Does anyone backup the system before updating?

I don't think anyone would have a backup of "1.0" because that sounds like a launch version. The first version installed in Motif ES at the factory. I haven't ever seen launch firmware released as an OS update file for keyboards.

A google search finds 1.02:

https://web.archive.org/web/20060509072944/https://www.yamahasynth.com/download/motif_series/mre102w.zip

If you really did program firmware intended for a different unit -- and the updater let you partially update -- then it's very likely you've "bricked" your unit and require service. Either using a jtag cable to flash the firmware or physically removing, reprogramming, and reinstalling the parts. They are not socketed. This would be a service event. More likely a tech would advise swapping out the entire DM board (... or whichever board has the firmware).