Hello ,
From CLI can you paste the outputs of :
> show chassis routing-engine
> show security monitor performance spu
> show security monitor performance sess
>show system processes extensive
>show system processes memory
>show system users
> show chassis alarms
> show system alarms
> show system core-dumps
>show system connections
>show system statistics
>show system buffers
>show chassis forwarding
> show chassis environment
Try power down the box and power up after 15 mins and check still do you see any high CPU or temp .
Once we have the outputs , we can check . Also if possible open a JTAC ticket so that is there is any HW issue or cooling issue , we can ask for replacement . Make sure you have proper cooling environment and nothing interupting the side airflow vent in SRX .