Rescued Hedgehog passed away

I rescued a hedgehog yesterday and he passed away at some point in the night. I’m gutted and really need to know if it was something I have done while caring for him. I put him in the shed in a box with a hot water bottle from 11pm would it have been too cold for him in there? Also I removed a tick from him and am now worries that it may have regurgitated the blood. Would this have killed him so quickly if he had been poisoned or infected by the tick regurgitating? So upset I couldn’t save him at really need to know if this was my fault or not. If anyone has any ideas I’d appreciate you getting in contact. Thanks in advance