You must have : External DVD and USB Hub with power.
I found W510 preboot faster than usb device become ready.
Befor you can boot from External DVD you must disable safe boot first.
How? ...
1. Go to cmos (Power On + Volume-)
2. Tab "Security" then set supervisor password. Now you able to change Safe boot setting in "Boot" Section. And change f12 boot menu too.
2. Tab "Boot" Change 'safe boot' to 'Disable'
3. Tab Exit and Save.
Trick for boot from DVD
1. Connect External DVD with USB Hub and Connect to power source.
2. Insert Recovery DVD label "System DVD" (All DVD include from iconia package.)
3. After insert "System DVD" Wait about 2-3 second for prepare External DVD to become ready.
4. After 2-3 sec, Plug usb to Iconia and hit F12 quicky.
5. You will see Boot Menu with External DVD, If not do 1 - 4 again
6. START RECOVERY!!!!
Sorry for very bad in english lang. 