I'm going from Shenzhen, Luowu to Dongguan, Grand Mercure Humen Hotel, Humen Ave by bus.

Well, you can take a bullet train from SZ to Dongguan first, which takes about 40 minutes and CNY58.5 for a first class seat, CNY53.5 for a second one.
After that, take metro line 2 to Humen Railway Station and leave from Exit A, take bus L1 to Taiping Xin Renmin Yiyuan. Walk southwest along Humen Avenue for 5 minutes, you will see it.

Thanks a lot ms Gloria. Appreciated.