galaxy s6 twrp problem

i have a g920f with 6.0.1 and i want to install Alliance rom. I have flashed spacex kernel and flashed twrp mm by ManhIT both using odin. (i also tried to use cf autoroot and flashed twrp but got stuck in bootloop). the problem i am facing now is that my twrp is not working when i am in twrp and i try to get out of it it gets stuck(by any option reboot, poweroff etc) but if i restart my device it will turn on like any normal device. Should I Flash alliance rom using twrp and boot it using restart method? or should i solve the twrp problem 1st?
Any Help is appriciated as i am a noob and this is my 1st phone by samsung
Thanks in Advance