Which - here are the best things I can recomend, IN THIS ORDER:
First, pull power to everything DirecTV related for an hour. All receivers, the power supply for the slimline switch or LNB.
Then, plug in ONLY the power supply for the switch/lnb and the receiver that is having trouble. Boot it up, see if you can get anything.
Second, check in the satellite setup screen to be sure you are on the Slimline 5 lnb dish option. There are several options now, I think the one you want is 3rd or 4th on the list, something like that. If you have one that is several down on the list, it may be wrong.
If you still have no signal, press the red reset button again and do a software download, anytime today. This will download the national release. You start the download the same way you start the CE download, 02468.
Still no luck - Format the drive. Press the red reset button, at the first blue screen, hold the RECORD button and DOWN arrow ON THE FRONT PANEL. Keep holding them until the "almost there" screen goes away. **I'm not 100% sure it's the down arrow, another reference I found said the LEFT arrow. It should be one of them - I know the Record button is the other button **
Formating the drive is the same as the "reset everything" option, and deletes all settings.
Lastly, if none of those work, your box probably needs to be replaced. Call DirecTV tech support, describe that it "won't turn on" (since you've already done all the troubleshooting) and ask for a replacement. The replacement is free with the protection plan, or $19.95 shipping without the replacement plan. There should be no additional contract or anything else. Replacements are almost always refurbs, but the boxes are leased and owned by DirecTV, so that's how it is.
This is very rare that a firmware download could cause a problem with the box that can't be reticified, but it is possible.
Lastly, if calling support for a replacement, DO NOT discuss the CE program or download. Tech support is not trained / knowledgable on the CE program.
Good luck.