Brake and engine at fault

2005 Jaguar S Type R with 50,000 MI
I was going about 35 miles per hour and most of
my dashboard lights went on ( break at fault
engine at fault) I shut it off and turn it back on and
it was working fine once I got home I tested my
battery and a couple other things I realized that my
battery is pretty weak ( 9 years old and Under 12
volts) so I bought a new battery took it out for a
test drive same thing happen driving around 35
miles an hour most of my dashboard lights went
on car is still running but if you try to speed up it
would not work it would only go about 4 miles an
hour as if you put a  car into a drive and just let it
roll