Radio draining battery
 

Hello. First post so apologies if this has been covered.
Probably for the third time in 15 years I have had to replace the radio in my car. I got the recon unit back , now fitted with Bluetooth, about 2 weeks ago.
However, over the weekend I found that the car was completely dead. No power whatsoever. This car isn't used as much these days but I do go to the trouble of giving it some time out normally twice a week.
Consequently, I charged the battery up fully which took some hours but I doubt it could have drained so fast that it was through lack of use.
When I parked the car up last night having reconnected the battery, it was dark. I was then able to see that upon taking the key out of the ignition, the Speedo binnacle illumination came on!! Upon putting the key back in and turning to first or second position the illumination went out. The only thing to have changed in the last two weeks was the radio and I recalled that I had to send a previous unit back as it also drained the battery.
A quick bit of investigation this morning showed that upon disconnecting the white wiring block from the top centre at the rear of the unit allows the ignition key to be removed from the car without any binnacle illumination. Reconnect the white wiring block with the car key removed and the illumination re appears.
I just wanted to check before contacting the radio supplier that it is possible/likely that something inside the radio is shorting/powering the illumination problem. This wasn't happening before switching units?

Any thoughts would be gratefully received

Many thanks

Mark