No sim card when boot phone whilst charging

Bit random but if I boot my nexus 5 whilst it's on charge then it will boot and show 'no sim card'. When the phone boots whilst it isn't on charge then it will load normally. When it goes on charge though it will ultimately show 'no sim card' again.

Tried a factory reset but hasn't helped. Likely to be hardware problem or a software glitch?

I've tried booting it in different ways and it does seem to be the phone being on charge that makes the difference. Weird one.

Thanks.