I fixed mine SX Pro, what i did:
1. Left it for like 20 minutes for charging from my PC via my phones microusb cable (CAUTION, IT WILL BECOME VERY HOT)
2. Turned off my switch with boot.dat on card and card into console
3. Put the Jig, put SX Pro WITH cable and current charging from PC
4. Hold VOL+ button and very-very quick disconnected micro-usb dongle and pressed power button while holding VOL+, it took less then a second
5. Dongle flashed green LED very quick and started to load payload with blue LED
Now it's working fine every time, don't know if this steps did any help or just 20 minutes charging worked, but anyway, may be if it will help someone with exact same problem
Before this i was seeing just a qick flash of green LED into RCM and payload loading with blue LED haven't started. So that was some kind of caps problem