Mobile menu not working – Android

The mobile menu is not working when I test it on my Samsung Android phone. I have disabled all the plugins one by one and it hasn’t fixed the issue. I disabled ALL the plugins and there was no change. The website is http://www.farmweld.com.au I noticed that there has been a sudden increase in my bounce rate on the 19th January and wonder if this is when the menu originally malfunctioned, possibly due to an update.

I am not a web designer, just a novice so if there are any instructions please make them simple 🙂