take two cables that are 10 or 15 feet long, connect them straightly to ur battery, from there measure the cables with a multimeter to check if there´s actual power flowing.
If not in possesion of a meter then just use a car light or other 12v lightbulb and connect it.
When u ensured u got power on the cables use them to connect the HU and only the HU. (note that a lot of HU´s only work when both memory and main power are connected) See if it works, probally will which takes you to the next thing: the amplifier
Just take the amp out, connect the loose´plus wire to the remote and the power connection on the amp, ground goes straight to ground on the amp.
Amp should turn on. If both worked fine then you need to play with the remote. Best thing to do is (if both worked in test scenario above) to connect it back on normal power just like u did above and see if it still works, if so then use the power going to the amp on both the remote and the normal power connection, the lamp will turn on regardless of the state of the HU, try turning the HU on after that...
hope it helps, basically you want to test ur setup without using ur car at this time..