My Samsung hmx-f80 turns on then immediately turns back off

This merely means that the gearing covering lens focusing is damaged and requires repair.

Link to Manual :

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjvj4jgm8fPAhXFLMAKHWbgDSsQFggcMAA&url=https%3A%2F%2Fcontent.abt.com%2Fdocuments%2F44220%2FHMX-F80P-ENG-IB-0109.pdf&usg=AFQjCNHUTkr_KS3vsAEJO-Tfc8WLOM_fFQ&bvm=bv.134495766,d.d2s

may be this video can help...

take the cover off and way ya goo replace it put the cover back on and play

You may view/download a copy of the manual at Owners Manual User Guide for Samsung HMX F90 HD Camcorder White

It's 110 pages. You can print it yourself, or take it to an office-supply store or printing company and have them print (and bind) it.

You may download a copy of the manual at http://downloadcenter.samsung.com/content/UM/201302/20130202113021637/HMX-F90-ENG_US-IB_130201.pdf

Use the Format command in the Settings menu. See page 80 of the manual: http://downloadcenter.samsung.com/content/UM/201302/20130202113021637/HMX-F90-ENG_US-IB_130201.pdf

Replace the data card or format it and try using the old one. They do wear out also if the date card is LOCKED you will get card error.

Best of it
Gary @ Fix Ya

I found some on Amazon by searching for "HMX-100N charger".

Click on the following link and you should have your manual. I am assuming that you have the HMX-U10 series. If not, let me know and I can find the right one. Remember to rate this solution if it helps!

http://org.downloadcenter.samsung.com/downloadfile/ContentsFile.aspx?CDSite=US&CttFileID=2434256&CDCttType=UM&ModelType=N&ModelName=HMX-U10RN&VPath=UM/200909/20090928120232390/HMX-U10N-ENG-IB-0924.pdf