Alt & Cl99 Blinking

Probably something asked before. What would be the best method to get the cable back up and running, the box was going slow for a while on changing channels, bring up the guide and wouldn't delete DVR shows that were recorded and then I power it off and on but doesn't turn back on to the guide or anything. I tried the basic troubleshoot by just unplugging for a while and when plugged back in took a while after saying boot to start downloading. Now it has been on a screen that says download progress 99% and Alt and Cl99 keep blinking on the box. Has been like that for about 4 hours. Says do not power off when it is downloading so didnt want to mess something up. Anyone have any answer for it?