I answer questions for free.
I specialize in timers and electrical devices.
I hesitate to answer about Malibu power packs because there are no parts or repairs for a power pack, and the owners of this product are angry that such an expensive item is unrepairable and then they downvote a truthful answer that is provided for free.
Here's what I've done for fixya customers.
For hours, I searched Intermatic Timers, Malibulights.com, and the web looking for parts and solutions for the Malibu power pack. There are no parts or solutions.
I purchased a power pack from Home Depot and examined it and then read the manual from head to toe.
The answer is this: if the power pack is not working for any reason and the receptacle has power, then the power pack is busted and you need another one.
However I can save you money on your next power pack, and that may be worth your trouble coming to fixya:
Your next power pack:
1) Match up wattage of bulbs with wattage of power pack.
15 each - 20 watt bulbs = 300 watts = 300 watt power pack ... if you buy the 500 watt power pack for 300Watts of bulbs, then it will burn up the bulbs and the power pack.
2) Replace bulbs as soon as they burn out or other bulbs will burn out and the power pack will burn out
3) When working on bulbs, unplug power pack or the power pack may burn out
4) Use the link below to help plan your low-voltage lighting
http://www.malibulights.com/guides_support/low_voltage_planning_guide/select_your_power_packPurchase a power pack:
Home depot sells Malibu power packs.
Lowes sells a Low-voltage power pack similar to Malibu