If you have got no hdmi, which is an extremely common failure on these sets, then you have, at minimum, a bad A board.
The problem is typically with finding them - these plasmas are now obsolete and for a 2005 model it is already well past its service life. It can be fixed, the the price of the board alone, if it can even be found, will be in the $300 range as they are in very short supply and have been in high demand over the years. Even that board may not be sufficient to fix the underlying video issue which could be coming from half a dozen other boards that are equally difficult to find.
For a tv of this age and resolution (only 720p capable) I'd hesitate to make any investment in it at this point. I realize you've already replaced it, but you could buy a brand new LED tv for the same amount you'd spend just on parts, with no guarantee it would even resolve the problem.
If you'd like to proceed, I'd be happy to help with trying to find parts and work through the repair process though. Personally, I'd cut my losses and move on at this point, the tv has lasted years past what it was designed for and given more value already than could reasonably be expected of it.
Best regards, ***** ***** for the news,
I am an independent technician and I've spent my personal time, unpaid, in an effort to assist with the question for which you solicited my services. This site works on the honor system, and to that end, I have prioritized working with you ahead of other paying customers.
Although you’ve already paid your fee to the site, I am only compensated for my efforts when customers such as yourself leave positive feedback for my work. Again I apologize there is not a better outcome here, though this is really beyond either of our control. I do hope you’ll consider leaving a 5 star rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately.