Tried to update my mac mini 2010 last night, downloaded "free update" but then opted for clean install, did not proceed with the install menu and rebooted to see whether Mavericks will appear in the recovery mode (cmd+R). But all I got at the reboot was a white screen. Resetting SMC didn't do anything, I can't reset PRAM with either wired or wireless keyboard (no second reboot), apparently the USB ports don't work (tried to attach an external HDD and pen drive), changing the HDD doesn't do anything, and Disk Utility shows everything is fine with the SSD drive I had inside the mini. Tried disconnecting both drives and all temp sensors as Service Manual troubleshooting section suggest - didn't change anything - white screen, folder with a question mark does not appear. The manual suggests mainboard failure which seems very odd to me, since it has been working just fine before the Mavericks download/reboot. Any ideas what could be the problem?