I'm probably the only Amiga User/ Fan in Korea or even all of Far East Asia. So, I only got this forum left.
I bought a Sam 460ex, with a Radeon HD 1MB, 2 GB RAM and 160 GB HD from an Italian banker named Luigi.
The Amiga arrived with heavy damages on its Commodore case, but works fine after replacing the hard disc.
He put in a legal version of Amiga OS 4.1 update 2. After update 5 the screen goes blank.
Please check out my video:
https://www.dropbox.com/s/ip18fuwi2v2wp ... 4.mp4?dl=0
U-Boot is using the Radeon card for starting up the Kickstart. After the kickstart takes off, the screen for onboard VGA goes blank.

I connected the Radeon card on HDMI and onboard with VGA.
I ordered Update 8 ages ago, but shipment time from Europe to Korea takes 4/5 weeks
I'm thankful for any idea how to fix it...
Cheers,
Manu san