Radioshows blue back light, no sound.

Couple of times making/breaking contact of the power supply cable or battery connection has brought the radio to life.
Radio then performs well on all available stations and fuctions perfectly untill it is eventually switched off.

When switched on again the radio will not work, making/breaking power contact will not result in a working radio as before.
On occasions when the radio has not been used for weeks/months the contact interference will then get it to play again untill the next switch off.

Any advice would be gratefully accepted. (i have no radio repair experience!)

Big Al., April 2016