I washed everything off under the hood of my 90 Honda Accord LX now it won't start?

I just purchased the car and it seems as though there was a oil leak at one point because everything was caked in grim and oil from the engine to the under carriage. I washed everything off under the hood with my house hose and baking soda a rag and tooth brush for hard to reach areas. I scrubbed the engine because it was black due to oil burning on it over a long period of time. It's now shiny and looks almost new but this morning I went to start the car and nothing. My neighbor came and gave me a jump it started right up but the second the jump cable was removed it just shut right back off tried again this time leaving cables on a bit longer but same thing it turned right back off with removal of cable. What could be wrong? Also my battery light is now on

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