To answer your first question Yes Jesus did go down to hell. We can see in Mathew 12:40 that Jesus will spend three days in hell.
(Mat 12:40) For as Jonas was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth.
Jonah 2:2 Shows us that the heart of the earth could be a direct reference to hell as you can see below.
(Jon 2:2) And said, I cried by reason of mine affliction unto the LORD, and he heard me; out of the belly of hell cried I, and thou heardest my voice.
Ephesians 4:8-10 Also shows us that Jesus descended to the lower parts of the earth.
(Eph 4:8) Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men.
(Eph 4:9) (Now that he ascended, what is it but that he also descended first into the lower parts of the earth?
(Eph 4:10) He that descended is the same also that ascended up far above all heavens, that he might fill all things.)
So yes Jesus did go down to hell. Now what he did there is a little different than what you were told.
We can see in 1 Peter 3:19 that he actually preaches to the spirits that were in the prison. So after he died in the flesh he went down to the lower regions and preached to the spirits that were in prison.
(1Pe 3:18) For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit:
(1Pe 3:19) By which also he went and preached unto the spirits in prison;
(1Pe 3:20) Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.
It is believed that the spirits that are in prison are the spirits of the old world (Before Noah’s Ark) and the fallen angles. You can see that above and in 2 Peter 2:4-5.
(2Pe 2:4) For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;
(2Pe 2:5) And spared not the old world, but saved Noah the eighth person, a preacher of righteousness, bringing in the flood upon the world of the ungodly;
In conclusion Jesus does go down to hell after his flesh dies but when he gets there he preaches to the spirits. Now your friend may have meant that Jesus defeated the devil by defeating death. If you remember the Devil tricked Adam and Eve into eating the forbidden fruit which in turn caused for man to die. When Christ dies and then is resurrected he defeats the Devil by ending the original sin of death as seen below.
(1Co 15:22) For as in Adam all die, even so in Christ shall all be made alive.
Hope this helps answer your question. If you need any more help with this just let us know. Thanks again for the question.
Thank you so much for your help! you said that Jesus preached to the fallen angels and old world souls..were any of them saved?would God except them if they repented even though they were in the "heart of the earth"?
Just so there is no confusion we wanted to make sure you knew that he preaches to the spirits in prison not the souls. It would appear that the spirits are not actually the souls of men. We have just begun looking into the differences between spirits and souls and so far have no definite answer for you. Now what he preaches to the spirits and fallen angels were not actually sure on what it is. According to Jude 1:6 we can see that the fallen angels are reserved in everlasting chains unto the judgment of the great day.
(Jud 1:6) And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.
This shows us that the fallen angels will not have a chance at repentance and will be in their everlasting chains until they are cast into the lake of fire. We were not able to locate anything on whether or not the old world souls of men would have a chance at repentance.
I know this doesn’t answer your question but I hope it helps a little. Thanks again.