Other than flushing the mess from the brake fluid after checking/getting the level right (eats paint) you may have some checking/adjusting to do.
Caliper slider pins checked & good (lubed) when doing the brakes?
Next check is to look at the calipers when brake is pressed (takes two people) to see which is moving when pedal is pressed.
Fronts shouldn't move appreciably - if they do, you'll need to recheck assembly there (including those pins) and see why they're "cocked" and flexing too much.
Rears could be moving more than normal for similar reasons, PLUS they may not be adjusted up yet (auto adjuster for E-brake). IF the pedal works fine (or better) with the E-brake handle up, you've found the issue & hopefully repeated application of the E-brake is all you need to get them adjusted up again.