First, a disclaimer. No actual description of hacking attempts are detailed in this post, just a write up of possible attack vectors.
Those huge electronic billboards in EDSA are so rampant that they now pose serious safety issues. Aside from that, they are also quite distracting and not so entertaining. But being a 1337 hax0r such as yourself, you can change that.
Hacking these billboards are not new, for example, this presentation in Defcon: https://www.youtube.com/watch?v=tpZ_NDx35u8, gives insight on what can be done to gain access to these devices.
But maybe you’re stuck in traffic and got bored:
https://www.techworm.net/2016/10/bored-hacked-billboard-show-steamy-video-says-arrested-programmer.html, what can you do?
Some of the attack vectors on this case study.