[Q] yellow traingle after cwm :( topic

hi all,

i just purchased this S2 I9100 handset from one of my freind..he had rooted and installed some kitkat resurrenction mix custom rom which i did not like

i flashed cwm through odin but when it rebooted in yellow traingle..i cna go into cwm recovery mode by presiing (vol up+power+home), yellow triangle appears briefly and then cwm menu appears..but when i select REBOOT SYSTEM it again goes into yellow traiangle..

i have searched on net and right now downloading stock rom from sammy I9100XWLST FOR indian s2 i9100LKAINU

my question is if i just flash this rom thru odin will the triangle go away? odin or copy to sd card and flash via cwm?

or do i have to download kernel seperately also,..where do i find if yes?

thanks