Vintage Synth Repair

hello all
i have a strange problem with my korg wavestation
when i power it up the logo korg appear then disappear and appear etc ....

i try the command 4 + down arrow at startup just after the display of the logo korg but nothing
when i plug a card it seems tio boot correctly because i can see during 1 sec the name of the last patch then reboot again

i have no idea
i battery inside was new

one more information i have this problem after sending a sysex
but what i don't understand is that early in the morning every works well i play with it, but after i want to try new sysex i found for WS, i use a software that works very well, i see he message on the display for the reception of data , i start playing with news patch but suddenly when i change the number of the patch to try another one, the WS reboot

i have a wavestation, it is not updated to the last rom version, and it is not the EX version

if you have any idea

thanks