Design was done in Eagle CAD and transferred to PCB via photosensitive film, etched and soldered. And now comes the "fun"part. It does not work.

when you connect lipo battery (4V~) to BAT connector, output from TPS61200 (connector 3.3V/ pads for ESP) is 6.01V (?!). Datasheet say that it can do MAX 5.5V (?!). But if you connect AA battery (1.2~V), the output is 3.3V. It seems like the booster mode works right, but the buck mode is somehow broken.

Any idea what might be wrong ?