1999 Chrysler Sebring no power, no start

My car just won't start. It went through various symptons

before completely losing all power. Except door lights and
head lights. All other electrical interior components are
not powered. At first, inner lights, doors locks and chime
came on and off at will. Then all other problems followed.
until my car just lost as said all power. Tried jumping to
no avail. Battery shows 12.2dcv. What 20 steps should
i try. Thankyou Derrick! Ps. I have a convertible, 2.5l