Start wont turn over after installing radio

[banpei]

Sounds indeed like a bad battery (or alternator not charging a lot) or a bad ground connection.

The 4age starter is prone to not start with suboptimal batteries. Use a multimeter to check the voltage on your battery (should be 12.2 volts) and start the engine (jump start) and check the voltage again and it should be above 13 volts for a normal charge (around 2000rpm).

If the alternator is to blame the voltage should be below 13 volts when the engine runs, however if this is normal and the battery also has a good voltage you may should check the main ground connection.