Several things can create reboot.
please do a few tests as below
1-disconnect Lnb /Lan cable from the rear .if reboot stops>.connect Lnb cable first .if reboot stop>connect lan cable. if by connect or discount still same
2-go to menu/setup/system/fan control increase fan speed about 2000+ press green button to save it.
3-If number 2/3 has not fixed it .Turn off the power open the top cover see if there is dust on the main board if so use paint brush clean all
4-If none above fix this unit >download latest 4 image from link below after that download boot load from 2nd Link. http://downloadtmsw.com/bbs/list.php?board=tmtwinoe