ok this is not a question, but something that may occur to someone as it has occured to me this time

the next thing I was upgrading a WL500g of a friend from firmware 1.6.5.3 (official) to 1.7.5.6CR2 all going fine.
Device upgrade went allright, booted up again and worked 'perfectly' after fucking with his ADSL SpeedTouch modem to set it in bridge, and applying like 20-30 times PPTP passwords etc in the WL500g the device HUNG

after poweroff, the device booted up correctly Wireless was working, IP was assigned also. pinging 192.168.1.1 did work BUT
telnet was not responding, also websetup was not responding
nothing strange i thought, just tried the restore button (when powered on) no action followed, i tried the button when powering on and it went into RECOVERY mode
i uploaded CR2 again: restoration completed succesfully
after it was booted up again, Wireless etc was assigned but still telnet+websetup was dead. i've repeated this like 10 times but it had no harm.

very strange, after restoring 1.6.5.3 into his device
the wl500g booted up again correctly and came normally online

after restoring default configuration i've entered the needed things (his adsl device was in router mode again) and upgraded to CR2, it seems to work correctly now

so it looked like some nvram settings had been corrupted which prevented the device to bootup properly.

so for the rest i still don't have an explanation for this. maybe it's an idea to create a firmware resque sometime, which does not make use of nvram and restores it or something like that..