Sky plus has green light but seems to be stuck in standby?

Last night watched recorded programme, then deleted watched programme once completed then tried to watch another.
Sky plus froze so I tried unplugging from mains, leaving out for a while then reconnected to mains. This has usually worked before but result was no power to sky box when power reconnected.
Tried above again and after re-connecting, after a while green power light shows as on when pressing on power button on front of box. Tried remote and box buttons to get into listings but nothing happens. Tried second remote and same thing. In both instances remote red light shows on box front when using remote but Sky seems to be still stuck in standby despite green power light showing.
You can hear whirring type sound from plus box which stops after few seconds.
If you use remote box will swith on/off but when on no Sky display on tv. TV works ok on Ch 1 - 5 using TV remote.
Any suggestions or should I try the power out/in/hold backup button option for stuck in standby problems does this delete any saved recorded programmes?

Thanks in advance