booting tivo without cable connection

Hi,

I've got a tivo which used to be connected to the cable. It's got stuff recorded on the HD.
When I start it (without connection to the tv cable), it hangs on 'starting up' screen forever.
At some point, I fiddled with buttons combinations to make it complete the boot sequence and get to the menu.
But I can't make it do it again.

Anyone has any idea?

Thanks!

R.