This happens, don't worry. The battery has completely drained and will take a long time to replenish its charge. Plug your charger in using the AC wall adapter and leave it charging for 24+ hours.
The power station has overcharge protection, so this will not damage your battery. After charging for a day or two, check the battery; it should be working again. If not, please contact sales1@powerstation0.com for additional troubleshooting support.