My Passport did this yesterday. It got hot and drained the battery in about 5 hours. Then it suddenly stopped and was happy again. I think it was an email account trying to sync a lot of emails with attachments.
goto device monitor and check th cpu usage for the last 12 hour and check the battery usage for the last 12 hour and check the ram too post a picture here if you can and check what is causing the issue heating up is quite normal battery drain is normal only when the phone is on high use like some app is taking huge amount of cpu usage or high amount of ram