No power

What are you talking about? No engine power? No electrical power? Buss bar for the box?

Also do you have any warning lights on the dash lit? The CEL or Check Engine, a little symbol that looks like a motor? Anything? And if so, flashing or steady, red or yellow? You might be in 'limp mode', but that is just a possibility not a fact. And the CB~~ was it installed by a professional, automotive shop or DIY? Does the transmission seem OK, shifting as normal? If you answer tenspeed first, the basics, and my questions secondarily we will be better able to assist

The cd was DIY as far as the power connection. I am hoping he didn't discount the battery. The cargo area has it own power supply connecte to the battery to run the refrigerated box. Will roll foward in 1 gear but won't backup 2% grade. Can increase RPM in Netrual but not in gear. The following cade were prescent befor the work. These code the shop said were normal after the partical filter work and adjustment were made; so the power would not go into limp mode every 3 months and ned to be cleaned. P2457 exhaust gas cooling system performance p0402 "A" flow excessive detected. The new code: p040b exhaust gas tempeture.