when you say apparently hdmi failed, did you test the motherboard integrated VGA video port using a working VGA video cable and monitor?  If VGA works but hdmi does not, try replace cmos battery with a new battery and clear cmos settings via motherboard jumper.  If no video on VGA either, then you may have a no post issue. say your motherboard works except for hdmi, then you could install a simple Dell gpu such as this one w hdmi [URL]  
I have an Inspiron 660 that I'm happy with.   Apparently something in the integrated graphics failed because it will no longer drive an HDMI monitor (checked the monitor and it works). Is it possible to install an add-on graphics card to replace the integrated graphics? Thanks
Inspiron 660, replacing failed integrated graphics?