Review on ⚡ Astro Pneumatic 7760 Wireless Electrical Circuit Tester by Michael Vargas

I am disappointed with this tester and would like to leave a comment if anyone has a suggestion. I used it this week to test the 12 volt wiring in my truck (part of the pre-installed auxiliary switch box). First I measured with a multimeter and confirmed 12V. Then you used this astro tester to see how it works. I brought the probe to the 12v wire and touched the steel bolt in the engine compartment. Nothing at first. Tried a few more times. After about the 3rd try (without changing anything on the probe and still grounding myself the same way) I got a red light. My friend tried it and got light AND sound. Then I tried again and got both light and sound. But repeated attempts gave me the same different results: nothing, just light, light and sound. My friend is a bigger guy - more bulk. Is it important? Suggestions are welcome as the return period expires after 30 days and I cannot find any warranty information for this tester. Many Thanks.