No Power to Radio

Bonneville1962

Sorry to be a pain but ive already put this question on the wrong forum (Caravan Chat) anyway ive just bought a used Radio/CD in almost new condition for my caravan the wiring was already there so i wired it to ISO connector switched Radio on & it
lit up for about a tenth of a second then went off---i checked for blown fuses & were all ok---i tried a few more times switching on & off with same results----hope someone can help---thanks Ray