Naxa

Can the injectors be tested? I had them sent away but came back saying they couldn't. I had a dodgy injector, after replacing it, the car was miss firing. Which wasn't happening before the replacement. So I put the old injector back in, still missing! So we thought I may have broke a wire on the loom whilst pulling it out the way. I know the loom is common to fail. Brand new loom fitted, still missing! So this is the point I had them sent away for testing. I put them back in to move the car, now it won't start at all!! Any ideas or advice would be greatly appreciated! Thanks in advance