Hero (or Heron) of Alexandria (Greek: Ἥρων ὁ Ἀλεξανδρεύς) (c. 10–70 AD) was an ancient Greek mathematician who was a resident of a Roman province (Ptolemaic Egypt); he was also an engineer who was active in his native city of Alexandria. He is considered the greatest experimenter of antiquity and his work is representative of the Hellenistic scientific tradition. Hero published a well recognized description of a steam-powered device called an aeolipile (hence sometimes called a "Hero engine"). Among his most famous inventions was a windwheel, constituting the earliest instance of wind harnessing on land.He is said to have been a follower of the Atomists. Some of his ideas were derived from the works of Ctesibius.Much of Hero's original writings and designs have been lost, but fortunately, some of his works were preserved in Arab manuscripts. (OTL Heron)
Baghdad Battery/Parthia battery
These battery a very controversial so we assume we are talking about a timeline where they existed in Heron lifetime, and really were battery. This might include OTL or not.
He didn't invent them obviously but what if the improved them. Most of his inventions ended up in temple where they impressed the naive simple religious followers. So lets say he comes in contact with these battery(his work had already had a strong Babylonian influence OTL), they can give you some kind of divine feeling so they should suit his usual purposes.
But he isn't too happy with the strength of the electric shock people receive so he tinkers around until he amplifies it to the maximum.
Mostly he tries the shock effect on animals and a dead ones as well. Surprise the dead one moves again, now he realizes he is up to something. In the end he is convinced that he not only found the elusive vital energy that was wildly theorized already, but also build a device to harness it in small amounts.
Possible implication:
Now only its only a few steps to a Lazarus device, isn't it? That idea should occupy medicine for the next hundred of years. The craziest possible experiment would probably be an open head proto-neuro surgery which existed combined now with electrical brain stimulation.
A manned hot air balloon:
The Chinese man Zhuge Liang of the Shu Han kingdom, in the Three Kingdoms era (220–80 AD)used airborne lanterns for military signaling. These lanterns are known as Kongming lanterns 孔明灯). Trough his research into Pneumatics Heron should be familiar with some of the interesting qualities of air . Even without he just needs to see something light floating over a fire. So lets say he invents a manned hot air balloon like the one Woodman and Nott build to prove the Nazca Indians in Peru were at least theoretically capable to build such a vehicle watch their giant figures drawn on the ground from above.
Possible implication:
Very useful for surveillance in military operations and obviously for entertaining rich people.
Some kind of a self playing organ (or even an gramophone):
A gramophone is portably at least borderline ASB. But all the necessary parts were their. Wax, acid, and the diaphragm could be build with permanent instead of paper or other materials known at the time. Instruments that were precise enough to build the Antikythera mechanism should handle that as well.
The self playing organ on the other side is definitely well into his realm. Heron build pneumatic organs, one was the first device powered by a windmill. Already in OTL one of the earliest musical instrument to be automated was the organ, which is comparatively easy to operate automatically. The power for the notes is provided by air from a bellows system, and the organist or player device only has to operate a valve to control the available air. The playing task can be performed by a pinned barrel. The gramophone could evolve from such a device although it is a long shot.
Possible implications:
Probably stays a fancy expensive toy. Once you got paper you could improve with some kind of punching card system.
All of these combined with the advanced stuff Heron already build don't necessary change much. The real game changers are paper, printing press and steam engine, all quite far away. Although it would make the timeline a little more colorful. Any more ideas for possible butterflies following these inventions?