I have a TiVo HD DVR TCD658000 which was working fine awhile ago; now, though, it no longer generates video output. When I power up the unit, the green power light comes on and the hard drive/drive fan starts. However, no video output is generated; the attached TV screen is black. There's no post/startup at all - just a black screen. Also, when I push the format button on the front of the unit, no format indicating lights light up; finally, when I use the TiVO remote, none of the lights flash on the front screen. I'd like to know what might be wrong with my TiVO and whether or not it's worthwhile fixing. The TiVO has a lifetime subscription. In case it matters, I used to have a hard drive expander attached to this unit - currently no hard drive expander is attached. I'm pretty sure that this isn't related but I thought I'd mention it. One last observation - upon closer inspection, it looks light the green power light is very rapidly flashing - it's not solidly lit. Might this be a power supply issue? Thanks in advance for your help.