won't start

I have a 1968 mustang 2v-289 all stock. the has been sitting for about 3 months without any movement at all. The car was burning oil excessively and i now want to deal with this problem but it will not start. When i turn the key i lose all power/electricity. It does not even attempt to turn over soon as i turn the key power it gone. what could cause this??? i have charged the

To get the power back i have to take off the batt cables and put them back

the dome light is very bright and the batt is charged (tried in another car and started right up). What are some things that i can check.

any info appreciated

i will try that